media: dvb-usb-v2: af9035: fix ISO C90 compilation error on af9035_i2c_master_xfer

This fixes a 'ISO C90 forbids mixed declarations and code' compilation
error on af9035_i2c_master_xfer, which is caused by the sanity check added
on user controlled msg[i], before declaring the demodulator register.

Fixes: 7bf744f2 ("media: dvb-usb-v2: af9035: Fix null-ptr-deref in af9035_i2c_master_xfer")
Signed-off-by: Desnes Nunes <desnesn@redhat.com>
Link: https://lore.kernel.org/r/20240919172755.196907-1-desnesn@redhat.com


Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>