ARM: 5928/1: Change type of VMALLOC_END to unsigned long.

Makes it consistent with VMALLOC_START

Tested-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Andreas Fenkart <andreas.fenkart@streamunlimited.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>