selftests/mm: convert page_size to unsigned long

selftests/mm: convert page_size to unsigned long

Cppcheck warning:
int result is assigned to long long variable. If the variable is long long
to avoid loss of information, then you have loss of information.

This patch changes the type of page_size from 'unsigned int' to
'unsigned long' instead of using ULL suffixes. Changing hpage_size to
'unsigned long' was considered, but since gethugepage() expects an int,
this change was avoided.

Link: https://lkml.kernel.org/r/20250403101345.29226-1-siddarthsgml@gmail.com
Signed-off-by: Siddarth G <siddarthsgml@gmail.com>
Reported-by: David Binderman <dcb314@hotmail.com>
Closes: https://lore.kernel.org/all/AS8PR02MB10217315060BBFDB21F19643E9CA62@AS8PR02MB10217.eurprd02.prod.outlook.com/
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>