[media] au8522 Remove 0x4 bit for register reads

The second highest bit in the register value is an indicator to do
a register read, so remove it since now au8522_regread() inserts
the bit automatically.

Also remove a stray instance where we were actually trying to write
to the I2C status register, which was actually a read.

Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>