clk: at91: change to using endian agnositc IO

Change to using endian agnostic _relaxed IO accessors instead of __raw

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
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CC: Andrew Victor <linux@maxim.org.za>
CC: Nicolas Ferre <nicolas.ferre@atmel.com>
CC: Jean-Christophe Plagniol-Villard <plagnioj@jcrosoft.com>
CC: Mike Turquette <mturquette@linaro.org> (maintainer:COMMON CLK FRAMEWORK)
CC: Stephen Boyd <sboyd@codeaurora.org> (maintainer:COMMON CLK FRAMEWORK)
CC: linux-kernel@vger.kernel.org (open list:COMMON CLK FRAMEWORK)
Signed-off-by: Michael Turquette <mturquette@linaro.org>