fs/squashfs: Fix compilation error

Commit 401d1c4f ("common: Drop
asm/global_data.h from common header") broke compilation of squashfs
filesystem when CONFIG_CMD_SQUASHFS=y is enabled.

Compilation is failing on error:

    aarch64-linux-gnu-ld.bfd: u-boot/fs/squashfs/sqfs_inode.c:121: undefined reference to `le32_to_cpu'

Fixes: 401d1c4f ("common: Drop asm/global_data.h from common header")
Suggested-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Tom Rini <trini@konsulko.com>