libata: Updates and fixes for pata_at91 driver

Please consider the following updates and fixes for pata_at91 driver.

* Removed extra headers
	Here we need only static memory controller properties, which are
	contained in generic header at91sam9_smc.h.
	No need to include any specific headers for at91sam9260 SoC.

* No harsh BUG_ON for get_clk in set_smc_timing function
        get_clk is now performed in driver probing function,
	        probing fails if master clock is not available

* Fixed uint/ulong mess in calc_mck_cycles function

Signed-off-by: Sergey Matyukevich <geomatsi@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>