[media] st-hva: fix a copy-and-paste variable name error

The second check for an error on hva->lmi_err_reg appears
to be a copy-and-paste error, it should be hva->emi_err_reg
instead.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Jean-Christophe Trotin <jean-christophe.trotin@st.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>