[media] [PATH,1/2] mxl5007 move reset to attach

This patch move the soft reset to the attach function because with dual
tuners, when one tuner do reset, the other one is perturbed, and the
stream has errors.

Signed-off-by: Jose Alberto Reguero <jareguero@telefonica.net>
Reviewed-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>