ARM: dts: imx6q-tbs2910: add SATA PHY configuration

Configure SATA PHY transmit level, boost, attenuation and equalizer
parameters for long wire connections. TBS2910 contains a standard SATA
connector, so devices are typically connected with (longer) SATA cables.
And explicitly configuring these parameters avoids complaints about
"not specified" values in boot messages.

Signed-off-by: Soeren Moch <smoch@web.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>