binfmt_elf_fdpic: fix variable set but not used warning

Fix below kernel warning:
fs/binfmt_elf_fdpic.c:1024:52: warning: variable 'excess1' set but not
used [-Wunused-but-set-variable]

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: sunliming <sunliming@kylinos.cn>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20250308022754.75013-1-sunliming@linux.dev
Signed-off-by: Kees Cook <kees@kernel.org>

Author: sunliming

fs/binfmt_elf_fdpic.c

@@ -1024,7 +1024,7 @@ static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *params,
 	/* deal with each load segment separately */
 	phdr = params->phdrs;
 	for (loop = 0; loop < params->hdr.e_phnum; loop++, phdr++) {
-		unsigned long maddr, disp, excess, excess1;
+		unsigned long maddr, disp, excess;
 		int prot = 0, flags;
 
 		if (phdr->p_type != PT_LOAD)
@@ -1120,9 +1120,10 @@ static int elf_fdpic_map_file_by_direct_mmap(struct elf_fdpic_params *params,
 		 *   extant in the file
 		 */
 		excess = phdr->p_memsz - phdr->p_filesz;
-		excess1 = PAGE_SIZE - ((maddr + phdr->p_filesz) & ~PAGE_MASK);
 
 #ifdef CONFIG_MMU
+		unsigned long excess1
+			= PAGE_SIZE - ((maddr + phdr->p_filesz) & ~PAGE_MASK);
 		if (excess > excess1) {
 			unsigned long xaddr = maddr + phdr->p_filesz + excess1;
 			unsigned long xmaddr;