omap5_common: Re-work mmc boot to try SD and eMMC, correct root device

OMAP5 boards may have both eMMC (on MMC2) and an SD slot (on MMC1).  We
Update the default bootcmd to match what happens on AM335x where we try
SD first, and then eMMC.  In this case however, the hardware layout used
for powering both of these means that in the kernel eMMC shall be found
first as it is powered by a fixed regulator and SD found second as SD is
powered via the palmas which will result in deferred probing.

Tested-by: Aparna Balasubramanian <aparnab@ti.com>
Signed-off-by: Tom Rini <trini@ti.com>
usb: Prevent using reserved registers on DM36x usb

The musb driver defines and uses MUSB_CSR0_H_DIS_PING, however this
bit is reserved on the DM36x. Thus this patch ensures that the
reserved bit is not accesssed.

It has been observed that some USB devices will fail to enumerate
with errors such as 'error in inquiry' without this patch.

See http://www.ti.com/litv/pdf/sprufh9a for details.

Cc: Marek Vasut <marex@denx.de>
Cc: Tom Rini <trini@ti.com>
Signed-off-by: Andrew Murray <amurray@embedded-bits.co.uk>
Acked-by: Marek Vasut <marex@denx.de>