vfat support=m: cannot flash an alternative kernel while removing the running one

SRU Justification:

Impact: Removing the running kernel (perhaps because we want to rollback to a previous one due to a regression) result in a system with no support for fat filesystem, and thus with the inability to flash/install the alternative kernel in the boot partition

How to reproduce: boot the beagle board, remove the running kernel and then run flash-kernel (see below)

Fix: Compile in support for v/fat and necessary nls modules (codepage 437 and iso8859-1) (see the attached patch)

=====

flag@beaglexm:~$ uname -a
Linux beaglexm 3.0.0-11-omap #18 Mon Sep 19 11:03:17 CEST 2011 armv7l armv7l armv7l GNU/Linux

# here we remove the running kernel
flag@beaglexm:~$ sudo dpkg -P linux-image-3.0.0-11-omap
[sudo] password for flag:
(Reading database ... 26609 files and directories currently installed.)
Removing linux-image-3.0.0-11-omap ...
WARN: Proceeding with removing running kernel image.
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.0.0-11-omap /boot/vmlinuz-3.0.0-11-omap
update-initramfs: Deleting /boot/initrd.img-3.0.0-11-omap
The link /vmlinuz is a damaged link
Removing symbolic link vmlinuz
 you may need to re-run your boot loader[grub]
The link /initrd.img is a damaged link
Removing symbolic link initrd.img
 you may need to re-run your boot loader[grub]
Purging configuration files for linux-image-3.0.0-11-omap ...
Examining /etc/kernel/postrm.d .
run-parts: executing /etc/kernel/postrm.d/initramfs-tools 3.0.0-11-omap /boot/vmlinuz-3.0.0-11-omap

# ...but when we try to re-install the old kernel in the boot partition we suddenly find out
# that we don't have vfat support compiled-in
flag@beaglexm:~$ sudo flash-kernel
Using u-boot partition: /dev/mmcblk0p1
mount: unknown filesystem type 'vfat'

# ...and since the running kernel package has already been removed, we can't load the vfat module anymore
flag@beaglexm:~$ ls -la /lib/modules/

total 6
drwxr-xr-x 3 root root 1024 2011-09-19 12:36 .
drwxr-xr-x 17 root root 4096 2011-09-16 16:39 ..
drwxr-xr-x 4 root root 1024 2011-08-30 06:45 3.0.0-9-omap
flag@beaglexm:~$ lsmod
Module Size Used by
dm_crypt 16118 0
joydev 9588 0
smsc95xx 12679 0
usbnet 18565 1 smsc95xx
omap_wdt 4519 0
twl4030_pwrbutton 1369 0
omap2_mcspi 8120 0
gpio_keys 6500 0
leds_gpio 3633 0
usbhid 38987 0
hid 81145 1 usbhid
usb_storage 44426 0
uas 8222 0

by the way, vfat support is compiled-in in omap4 kernel.