ARM: l2c: avoid passing auxiliary control register through enable method

Avoid passing the auxiliary control register value through the enable
method.  In the resume path, we have to read the value stored in
l2x0_saved_regs.aux_ctrl, only to have it immediately written back by
l2c_enable().  We can avoid this if we have __l2c_init() save the value
directly to l2x0_saved_regs.aux_ctrl before calling the specific enable
method.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>