mfd: arizona-core: msleep() is unreliable for anything <20ms use usleep_range() instead

WARNING: msleep < 20ms can sleep for up to 20ms; see Documentation/timers/timers-howto.txt
+               msleep(1);

WARNING: msleep < 20ms can sleep for up to 20ms; see Documentation/timers/timers-howto.txt
+                       msleep(5);

WARNING: msleep < 20ms can sleep for up to 20ms; see Documentation/timers/timers-howto.txt
+               msleep(1);

WARNING: msleep < 20ms can sleep for up to 20ms; see Documentation/timers/timers-howto.txt
+               msleep(1);

total: 0 errors, 4 warnings, 1407 lines checked

Cc: patches@opensource.wolfsonmicro.com
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>