vendorcode/amd/agesa/f*: Improve gcccar.inc assembler compatibility.

A comparison with a two's complement in gcccar.inc has dubious
GAS/AT&T notation. Clang miss-parses 0x-1 as an invalid hexadecimal
number.

Change-Id: I88baa5c2513f062ff309df05916a3832b9bd9bb1
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/5277
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
5 files changed