Trying to resume l2x0 if it was not enabled before suspend leads to
system crash. This patch prevents this by checking if l2x0_regs_phys is
a valid pointer to l2x0 context data saved on initialization.
Signed-off-by: Tomasz Figa <t.figa@samsung.com> Acked-by: Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>