ARM: dts: hummingboard: add mSATA support for iMX6 quad/dual HummingBoard

Initial patch from Rabeeh, but with the electrical properties added.

Signed-off-by: Rabeeh Khoury <rabeeh@solid-run.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>