firmware.c: Fix 'dead assignment'

Dead assignment spotted out using clang-tools.

Change-Id: I44ca81ecee8ee9639b37a03e5a5b513cd07f4d10
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/em100/+/42843
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
1 file changed