ARM: 5958/1: ARM: U300: fix inverted clk round rate

The clk_round_rate() functions in the U300 clocking will always
select the lowest clocking frequency due to inverted rounding
comparisons. Fix this.

Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>