Fix omap1 clock issues

This fixes booting, and is a step toward fixing things properly:

- Make enable_reg u32 instead of u16
- Get rid of VIRTUAL_IO_ADDRESS for clocks
- Use __raw_read/write instead of omap_read/write for clock registers

This patch adds a bunch of compile warnings until omap1 clock
also uses offsets.

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