ARM: OMAP: 1/4 Fix clock framework to use clk_enable/disable

This patch fixes OMAP clock framework to use clk_enable/disable
instead of clk_use/unuse as specified in include/linux/clk.h.

Instances of clk_use/unuse are renamed to clk_enable/disable,
and references clk_use/unuse are removed.

Signed-off-by: Tony Lindgren <tony@atomide.com>