ARM: OMAP: DMTimer: Optimize by adding load and start

ARM: OMAP: DMTimer: Optimize by adding load and start

This patch optimizes the timer load and start sequence.  By combining the
load and start a needless posted wait can be removed from the system timer
execution path.

* Before patch register writes are taking up .078% @ 500MHz during idle.

 Address                 |total  |min  |max      |avr     |count|ratio%
 old\process\default_idle|7.369s |0.0us|999.902ms|14.477ms|509. |62.661%
 ld\Global\cpu_v7_do_idle|4.265s |0.0us|375.786ms|24.374ms|175. |36.270%
                (UNKNOWN)|17.503ms|0.us|531.080us|5.119us|3419. |0.148%
 r\omap_dm_timer_set_load|8.135ms|0.0us|79.887us|15.065us|540.  |0.069% <--
 \vmlinux-old\Global\_end|2.023ms|0.0us|4.000us|0.560us|3613.   |0.017%
 -old\Global\__raw_readsw|1.962ms|0.0us|108.610us|9.167us|214.  |0.016%
 old\smc91x\smc_interrupt|1.353ms|0.0us|10.212us|2.348us|576.   |0.011%
 s/namei\__link_path_walk|1.161ms|0.0us|4.310us|0.762us|  1524. |0.009%
 \omap_dm_timer_write_reg|1.085ms|0.0us|126.150us|2.153us|504.  |0.009% <--

* After patch timer functions do not show up in top listings for long captures.

Signed-off-by: Richard Woodruff <r-woodruff2@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>