spi: omap-uwire: use devm_ functions

This patch introduces the use of devm_clk_get and devm_ioremap instead
of the unmanaged interfaces and removes the corresponding free function
calls.

Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Mark Brown <broonie@linaro.org>