m7-common: camera: remove scene mode hacks

* HTC HAL now lists the HDR scene mode by default

Change-Id: Ia0328cc76f5a3630974adb286219e9cc3664258d
m7-common: camera: remove preview size hack

* HTC HAL now sets the right value for video snapshot sizes

Change-Id: Id997325f0ae95bf696cbe4ac83032ca012b52998
m7-common: camera: set front cam focus mode

* Front camera does not support any focus mode other than 'infinity'

Change-Id: I401f7d7ad30efc453393755ae299783175afbb45
m7-common: camera: set FFC focal length

Change-Id: I09305bb7896ad2278d4d1c39f75620fdcadf2f63