USB: ci13xxx_udc: Override param to draw more current

Sometimes battery may drain faster than charging rate.
In that case target may run out of power in few days
or run. Provide an override parameter which would
allow for more current to be drawn when connected
to SDP charger.

echo "600" > /sys/module/ci13xxx_msm/parameters/vbus_draw_mA
cat /sys/class/power_supply/usb/current_max
cat current_max
600000

Change-Id: I7d10a2f17357e492219eac7b18d649c5c526464f
Signed-off-by: Sujeet Kumar <ksujeet@codeaurora.org>