ARM: OMAP: Correct two bugs in arch/arm/mach-omap2/clock.c

omap2_clk_set_rate: dif_off must use clk->rate_offset, not clk->src_off.
omap2_get_src_field: for the case CM_SYSCLKOUT_SEL1, val must be 2 for
96MHz and 3 for 54MHz.

Signed-off-by: Jarkko Nikula <jarkko.nikula@nokia.com>
Signed-off-by: Juha Yrjola <juha.yrjola@solidboot.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>