omap4: l2x0: Construct the AUXCTRL value using defines

This patch removes the hardcoded value of auxctrl value and
construct it using bitfields

Bit 25 is reserved and is always set to 1. Same value
of this bit is retained in this patch

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>