ARM: tegra: Fix data type for io address

Warnings were generated because following commit changed data type for
address pointer

195bbca ARM: 7500/1: io: avoid writeback addressing modes for __raw_ accessors

arch/arm/mach-tegra/tegra30_clocks.c: In function 'clk_measure_input_freq':
arch/arm/mach-tegra/tegra30_clocks.c:418:2: warning: passing argument 2 of '__raw_writel' makes pointer from integer without a cast
.../arch/arm/include/asm/io.h:88:20: note: expected 'volatile void *' but argument is of type 'unsigned int

Signed-off-by: Prashant Gaikwad <pgaikwad@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>