OMAP3 hwmod: Add automatic OCP_SYSCONFIG AUTOIDLE handling

This patch fills in the OCP_SYSCONFIG.AUTOIDLE handling in the OMAP
hwmod code.

After this patch, the hwmod code will set the module AUTOIDLE bit
(generally <module>.OCP_SYSCONFIG.AUTOIDLE) to 1 by default upon
enable.  If the hwmod flag HWMOD_NO_OCP_AUTOIDLE is set, AUTOIDLE will
be set to 0 upon enable.  Upon module disable, AUTOIDLE will be set to
1.

Enabling module autoidle should save some power.  The only reason to
not set the OCP_SYSCONFIG.AUTOIDLE bit is if there is a bug in the
module RTL, e.g., the MPUINTC block on OMAP3.

Comments from Kevin Hilman <khilman@deeprootsystems.com> inspired this patch,
and Kevin tested an earlier version of this patch.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Tested-by: Kevin Hilman <khilman@deeprootsystems.com>