mtkmodem: naming refactors

 * struct mtk_data => mtk
 * GRil => ril
 * ofono_modem => modem

Signed-off-by: You-Sheng Yang <vicamo@gmail.com>
Merge branch 'refactor-mtk-var-naming' into mx4-porting

Conflicts:
	plugins/mtk.c
mtkmodem: add dummy RIL_REQUEST_DISABLE_VT_CAPABILITY

Signed-off-by: You-Sheng Yang <vicamo@gmail.com>
Merge branch 'disable-vt-cap' into mx4-porting

Conflicts:
	plugins/mtk.c