lib/test_vmalloc.c: use unsigned long constant

Use an unsigned long constant instead of an int constant and a cast.  This
fixes the checkpatch warning

WARNING: Unnecessary typecast of c90 int constant - '(unsigned long) 1' could be '1UL'
+     align = ((unsigned long) 1) << i;

Link: https://lkml.kernel.org/r/20240226191159.39509-4-martin@kaiser.cx
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>