s390/mm: Fix type mismatch in get_align_mask().

Commit 86f48f9 ("s390/mmap: disable mmap alignment when
randomize_va_space = 0") introduced get_align_mask() with return type of
'int', while the target field 'info.align_mask' in struct
vm_unmapped_area_info is 'unsigned long'.

With currently used masks, this should not cause truncation issues, but
fix it and return 'unsigned long' to avoid future problems.

Fixes: 86f48f9 ("s390/mmap: disable mmap alignment when randomize_va_space = 0")
Cc: stable@vger.kernel.org # v6.9+
Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Author: gerald-schaefer

arch/s390/mm/mmap.c

@@ -64,7 +64,7 @@ static inline unsigned long mmap_base(unsigned long rnd,
 	return PAGE_ALIGN(STACK_TOP - gap - rnd);
 }
 
-static int get_align_mask(struct file *filp, unsigned long flags)
+static unsigned long get_align_mask(struct file *filp, unsigned long flags)
 {
 	if (filp && is_file_hugepages(filp))
 		return huge_page_mask_align(filp);