spi-bcm2708: Prepare for Common Clock Framework migration

As part of migrating to use the Common Clock Framework, replace clk_enable()
with clk_prepare_enable() and clk_disable() with clk_disable_unprepare().
This does not affect behaviour under the current clock implementation.

Also add a missing clk_disable_unprepare() in the probe error path.

Signed-off-by: Noralf Tronnes <notro@tronnes.org>
BCM2708: Migrate to the Common Clock Framework

As part of moving towards using Device Tree, the Common Clock Framework
has to be used instead of the BCM2708 clock implementation.

Selecting COMMON_CLK removes the need to set CLKDEV_LOOKUP and HAVE_CLK explicitly.

CONFIG_ARCH_BCM2708_CHIPIT #ifdef's are removed. They are no longer in use.

Signed-off-by: Noralf Tronnes <notro@tronnes.org>
BCM2708: remove 'bcm2708_usb' clkdev

'bcm2708_usb' is currently not in use by the USB OTG driver.

Signed-off-by: Noralf Tronnes <notro@tronnes.org>
Merge pull request #630 from notro/clock

Migrate to the Common Clock Framework