mfd: ab8500-debugfs: Set the USB charging current to 300mA for ABV3

In case of AB-V3, the eye diagram related issues are resolved.
So, set the device charging current to 300mA when connected to
standard host. Also, add the USB PHY tuning values to improve
the USB eye diagram

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by:  <thirupathi.chippakurthy@stericsson.com>