staging: rtl8188eu: new variable for...

staging: rtl8188eu: new variable for hal_data->MCSTxPowerLevelOriginalOffset[pwrGrpCnt] in store_pwrindex_offset function

hal_data->MCSTxPowerLevelOriginalOffset[pwrGrpCnt] frequent in this function, so it replaced by the power_level_offset new variable.

Signed-off-by: Ivan Safonov <insafonov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>