[MIPS] TX49x7: Fix reporting of the CPU name and PCI clock

I've noticed that PCI clock was incorrectly reported as 66 MHz while being
mere 33 MHz on RBTX4937 board -- this was due to the different encoding of
the PCI divisor field in CCFG register between TX4927 and TX4937 chips...

Also, RBTX49x7 was printed out as a CPU name (e.g., "CPU is RBTX4937");
and some debug printk() were duplicating each other...

Signed-off-by: Konstantin Baydarov <kbaidarov@ru.mvista.com>
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>