fwts: need to make ACPIDUMP parser more robust

Feeding the fwts APCIDUMP parser data with extraneous spaces between the hex digits causes a segfault. This is because the number of hex digits read in is truncated and the parser reads in less than 16 bytes per line and allocates less than 16 bytes. One the next row read, the offset is greater than the table size been allocated so eventually we fall off the end of the table.

XENV @ 0x00000000
  0000: 58 45 4E 56 39 00 00 00 01 35 58 65 6E 56 4D 4D XENV9....5XenVMM
  0010: 54 45 4D 50 4C 41 54 45 00 00 00 00 49 4E 54 4C TEMPLATE....INTL
  0020: 14 02 14 20 00 00 00 10 00 00 00 00 00 20 00 00 ... ......... ..
  0030: 00 00 00 00 00 00 00 25 03 .......%.