Fix "is_e2" warning introduced by:

9ce3fa68 ARM: shmobile: rcar-gen2: Add CA7 arch_timer initialization for r8a7794

Only triggers on kernel configurations that have ARCH_ARM_TIMER=n.
Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>