ARC: remove checks for CONFIG_ARC_MMU_V4

There's no Kconfig symbol ARC_MMU_V4 so the checks for CONFIG_ARC_MMU_V4
will always evaluate to false. Remove them.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>