ARM: OMAP2+: hwmod code: add support to set dmadisable in hwmod framework

The DMADISABLE bit is a semi-automatic bit present in sysconfig register
of some modules. When the DMA must perform read/write accesses, the
DMADISABLE bit is cleared by the hardware. But when the DMA must stop for power
management, software must set the DMADISABLE bit back to 1.

In cases where the ROMCODE/BOOTLOADER uses dma, the hardware clears the
DMADISABLE bit (but the romcode/bootloader might not set it back to 1).
In order for the kernel to start in a clean state, it is
necessary for the kernel to set DMADISABLE bit back to 1 (irrespective
of whether it's been set to 1 in romcode or bootloader).

During _reset of the (hwmod)device, the DMADISABLE bit is set so that it
does not prevent idling of the system. (NOTE: having DMADISABLE to 0,
prevents the system to idle)

DMADISABLE bit is present in usbotgss module of omap5.

Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
[paul@pwsan.com: updated to apply; fixed checkpatch warnings]
Signed-off-by: Paul Walmsley <paul@pwsan.com>