board: tablet: usb: coexisting both HSIC and PHY in single kernel binary

Added kernel command line parameter 'omap4_tablet_uses_hsic' that
allows to have both HSIC and PHY in single kernel binary for Tablet2,
this allows to enable HSIC changing only kernel command line

Usage: pass 'omap4_tablet_uses_hsic' to kernel through command line in case
of HSIC modifications on Tablet2. Do naot apss it in case of
traditional PHY usage.

Change-Id: I0c50a1af18a26b06ca3957b21c7fa707d870428b
Signed-off-by: Ruslan Bilovol <ruslan.bilovol@ti.com>