charger: bq24773: Fix read input current error
charger: bq24773: Fix read input current error

'ectool chargestate show' shows the wrong input current since
the function charger_get_input_current() uses REG8_TO_CURRENT.

BUG=None
TEST=Use 'ectool chargestate show' or UART command 'charger'
     check the input current value.
BRANCH=None

Signed-off-by: james_chao <b798efe4ec4ac46ab52dc37fd8c2f2db6ce423d1@asus.com>
Change-Id: I29229ea1ef22811035b500c7a33fedee6562db35
Reviewed-on: https://chromium-review.googlesource.com/259842
Reviewed-by: Shawn N <5259333ce42e3ace6a73988cec7115ed9d3a661a@chromium.org>
Reviewed-by: Divya Jyothi <7fa6690d0a542ccce445e16fba24c5f6700e0873@intel.com>
Reviewed-by: Randall Spangler <62698fdbb84d1779579ee80c3f39fac22017e5bc@chromium.org>
Tested-by: Divya Jyothi <7fa6690d0a542ccce445e16fba24c5f6700e0873@intel.com>
Commit-Queue: Shawn N <5259333ce42e3ace6a73988cec7115ed9d3a661a@chromium.org>

akappy7/ChromeOS_EC_LED_Diagnostics,md5555/ec,md5555/ec,fourier49/BZ_DEV_EC,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,fourier49/BIZ_EC,md5555/ec,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,fourier49/BIZ_EC,akappy7/ChromeOS_EC_LED_Diagnostics,md5555/ec,coreboot/chrome-ec,fourier49/BZ_DEV_EC,fourier49/BIZ_EC,fourier49/BZ_DEV_EC,coreboot/chrome-ec,fourier49/BZ_DEV_EC,fourier49/BIZ_EC,coreboot/chrome-ec,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics