OMAP4: dma: Correct CPU version check for dma_common_ch_end

CCDN is the last common channel register in all OMAP4 versions. Use
cpu_is_omap44xx() instead of the cpu_is_omap4430().
cpu_is_omap4430() returns 0 unconditionally. This causes that the
dma_common_ch_end register variable is not configured correctly on OMAP4, not
even for OMAP4430.
Because of this, registers between CCFN - CCDN will be not cleard in the
omap2_clear_dma function in OMAP4.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>