dm: x86: Remove ebp assembler warning in zimage.c

This code generates warnings with recent gcc versions. We really don't need
the clobber specification, so just drop it.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/x86/lib/zimage.c

@@ -282,7 +282,6 @@ void boot_zimage(void *setup_base, void *load_address)
 	:: [kernel_entry]"a"(load_address),
 	   [boot_params] "S"(setup_base),
 	   "b"(0), "D"(0)
-	:  "%ebp"
 	);
 }