arm: Remove #include <version.h> from armv8/fwcall.c

No version information is used in armv8/fwcall.c therefore do not include
version.h header file. This change prevents recompiling fwcall.o when
SOURCE_DATE_EPOCH changes.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Simon Glass <sjg@chromium.org>