media: dvb_ca_en50221: Refactored dvb_ca_en50221_thread

Refactored "dvb_ca_en50221_thread" by moving the state machine into the
new function "dvb_ca_en50221_thread_state_machine". This reduces the
thread function size and reduces the structural complexity and of course
gives us more space to meet the line length goal in the new function.
Signed-off-by: Jasmin Jessich <jasmin@anw.at>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>