arm: omap4: 4430sdp: drop ehci support

Most revisions of the OMAP4 Blaze/SDP platform do not have
the EHCI signals routed by default. The pads are routed
for the alternate HSI functionality instead, and explicit
board modifications are needed to route the signals to
the USB PHY on the board.

Also, turning on the PHY connected to the EHCI port causes
a board reboot during bootup due to an unintended short
on the rails - this affects many initial revisions of the
board, and needs a minor board mod to fix (or as a
workaround, one should not attempt to power on the
USB PHY).

Given that these boards need explicit board mods to even
get EHCI working (separate from the accidental short above),
we should not attempt to enable EHCI by default.

So drop the EHCI support from the board files for the
Blaze/SDP platforms.

Signed-off-by: Anand Gadiyar <gadiyar@ti.com>
Cc: Keshava Munegowda <keshava_mgowda@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>