ARM: OMAP2+: hwmod: call to _omap4_disable_module() should use the SoC-specific call

The hwmod code unconditionally calls _omap4_disable_module() on all
SoCs when a module doesn't enable correctly.  This "worked" due to the
weak function omap4_cminst_wait_module_idle() in
arch/arm/mach-omap2/prcm.c, which was a no-op.  But now those weak
functions are going away - they should not be used.  So this patch
will now call the SoC-specific disable_module code, assuming it
exists.

Needs to be done before the weak function is removed, otherwise AM33xx
will crash early in boot.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Tested-by: Vaibhav Hiremath <hvaibhav@ti.com>