ARM: OMAP3: PM: remove superfluous calls to pwrdm_clear_all_prev_pwrst()

Remove some superfluous calls to pwrdm_clear_all_prev_pwrst().
pwrdm_pre_transition(), which appears a few lines after these calls,
invokes pwrdm_clear_all_prev_pwrst() on each powerdomain -- there's no
need to do it twice.

N.B.: some of us have observed that accesses to the previous
powerstate registers seem to be quite slow.  Although the writes
removed by this patch should be buffered by the write buffer, there is
a read to a PRM register immediately afterwards.  That will block the
OMAP3 MPU until all of those writes complete.  So this patch should
result in a minor performance improvement during idle entry.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Tero Kristo <t-kristo@ti.com>
[khilman@ti.com: removed a couple more for OMAP4]
Tested-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>

arch/arm/mach-omap2/omap-mpuss-lowpower.c

@@ -263,12 +263,10 @@ int omap4_enter_lowpower(unsigned int cpu, unsigned int power_state)
 	 * In MPUSS OSWR or device OFF, interrupt controller  contest is lost.
 	 */
 	mpuss_clear_prev_logic_pwrst();
-	pwrdm_clear_all_prev_pwrst(mpuss_pd);
 	if ((pwrdm_read_next_pwrst(mpuss_pd) == PWRDM_POWER_RET) &&
 		(pwrdm_read_logic_retst(mpuss_pd) == PWRDM_POWER_OFF))
 		save_state = 2;
 
-	clear_cpu_prev_pwrst(cpu);
 	cpu_clear_prev_logic_pwrst(cpu);
 	set_cpu_next_pwrst(cpu, power_state);
 	set_cpu_wakeup_addr(cpu, virt_to_phys(omap4_cpu_resume));

arch/arm/mach-omap2/pm34xx.c

@@ -290,11 +290,6 @@ void omap_sram_idle(void)
 	int core_prev_state, per_prev_state;
 	u32 sdrc_pwr = 0;
 
-	pwrdm_clear_all_prev_pwrst(mpu_pwrdm);
-	pwrdm_clear_all_prev_pwrst(neon_pwrdm);
-	pwrdm_clear_all_prev_pwrst(core_pwrdm);
-	pwrdm_clear_all_prev_pwrst(per_pwrdm);
-
 	mpu_next_state = pwrdm_read_next_pwrst(mpu_pwrdm);
 	switch (mpu_next_state) {
 	case PWRDM_POWER_ON: