[ARM] 3386/1: AT91RM9200 Clock update

Patch from Andrew Victor

This patch includes a few changes to the clock support on the
AT91RM9200.

1. Added definitions for Ethernet, MMC, TWI, USARTs, and SPI peripheral
clocks.

2. Replaced some hard-coded hex values with the text definitions in
at91rm9200_sys.h.

3. If the USB96M bit is set for PLLB, then the rate of PLLB is not
affected but only the USB Host/Device clocks which are derived from it.
Issue reported by Sergei Sharonov.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>