Remove unused variable

warning: variable 'isMPEG4' set but not used [-Wunused-but-set-variable]
warning: variable 'inchar' set but not used [-Wunused-but-set-variable]

Test: build & boot
Change-Id: If87addbb9501cdb5cf540a8d281ffc86086a0e60
Signed-off-by: guochuang <guochuang@xiaomi.corp-partner.google.com>