[CPUFREQ] S5PV210: Adjust udelay prior to voltage scaling down

Voltage scaling accesses the MAX8998 regulators over bit-banged I2C
with lots of udelays.  In the case of decreasing CPU speed, the
number of loops per us for udelay needs to be adjusted prior to
decreasing voltage to avoid delaying for up to 10X too long.

Signed-off-by: Todd Poynor <toddpoynor@google.com>
Signed-off-by: Jonghwan Choi <jhbird.choi@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Dave Jones <davej@redhat.com>