x86/boot: Remove unused function __fortify_panic()

That function is only used when the kernel is compiled with FORTIFY_SOURCE and
when the kernel proper string.h header is used. The decompressor code doesn't
use the kernel proper header but has local copy which doesn't contain any
fortified implementations of the various string functions. As such
__fortify_panic() can never be called from the decompressor so remove it.
Signed-off-by: Nikolay Borisov <nik.borisov@suse.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240613110837.300273-1-nik.borisov@suse.com

arch/x86/boot/compressed/misc.c

@@ -531,8 +531,3 @@ asmlinkage __visible void *extract_kernel(void *rmode, unsigned char *output)
 
 	return output + entry_offset;
 }
-
-void __fortify_panic(const u8 reason, size_t avail, size_t size)
-{
-	error("detected buffer overflow");
-}