ARM: davinci: uart: move to devid based clk_get

For modules having single clock, clk_get should be done with dev_id.
But current davinci implementation handles multiple instances
of the UART devices with single platform_device_register. Hence clk_get
is based on con_id rather than dev_id, this is not correct. Do
platform_device_register for each instance and clk_get on dev_id.

Signed-off-by: Manjunathappa, Prakash <prakash.pm@ti.com>
[nsekhar@ti.com: actually stop using con_id in clk_get(), squash the
		 patch adding OF aux data into this one]
Signed-off-by: Sekhar Nori <nsekhar@ti.com>