ARM: S5P: VMALLOC_END should be unsigned long

Silences following build warning:

arch/arm/mm/init.c: In function 'mem_init':
arch/arm/mm/init.c:644: warning: format '%08lx' expects type 'long
unsigned int', but argument 12 has type 'unsigned int'

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>