tools/firmware: do not add a .note.gnu.property section

tools/firmware: do not add a .note.gnu.property section

Prevent the assembler from creating a .note.gnu.property section on
the output objects, as it's not useful for firmware related binaries,
and breaks the resulting rombios image.

This requires modifying the cc-option Makefile macro so it can test
assembler options (by replacing the usage of the -S flag with -c) and
also stripping the -Wa, prefix if present when checking for the test
output.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>