V4L/DVB (8028): Improve error messages for tda1004x attach

V4L/DVB (8028): Improve error messages for tda1004x attach

A fresh copy of v.29 firmware, using get_firmware, is leading to an invalid
firmware:

DVB: registering new adapter (saa7133[0])
DVB: registering frontend 0 (Philips TDA10046H DVB-T)...
tda1004x: setting up plls for 48MHz sampling clock
tda1004x: found firmware revision ff -- invalid
tda1004x: trying to boot from eeprom
tda1004x: found firmware revision ff -- invalid
tda1004x: waiting for firmware upload...
tda1004x: Error during firmware upload
tda1004x: found firmware revision ff -- invalid
tda1004x: firmware upload failed

Sometimes, loading/unloading this firmware makes tda1004x to return an invalid
ID. However, there were no printk messages to help to identify what were the
cause for the error.

With this patch, it will now print:

Invalid tda1004x ID = 0xff. Can't proceed
saa7133[0]/dvb: failed to attach tda10046
saa7133[0]/dvb: frontend initialization failed

Tested with LifeView FlyDVB-T Hybrid Cardbus/MSI TV @nywhere A/D NB

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>