media: s5p-mfc: Amend initial min, max values of HEVC hierarchical coding QP controls

Valid range for those controls is specified in documentation as [0, 51],
so initialize the controls to such range rather than [INT_MIN, INT_MAX].

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>