MIPS: PowerTV: Move register setup to before reading registers.

The 4600 family code reads registers to differentiate between two ASIC
variants, but this was being done prior to the register setup. This moves
register setup before the reading code.

Signed-off-by: David VomLehn <dvomlehn@cisco.com>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/1392/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>