x86, microcode, AMD: Release firmware on error

When the ucode magic is wrong, for whatever reason, we don't release the
loaded firmware binary and its related resources. Make sure we do. Also,
fix function naming to fit this driver's convention and shorten variable
names.

Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Acked-by: Andreas Herrmann <Andreas.Herrmann3@amd.com>