media: radio-si476x: rectify spelling and grammar

Change 'inaccesable' to 'inaccessible'
Change 'detrmine' to 'determine'
Delete 'in' grammatically

Signed-off-by: Xiaofeng Cao <caoxiaofeng@yulong.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>