omap: ldp: fix compile breakage and physical/virtual address usage

commit bf9454a3aaf2cad2321aa8f97bfd5d8c4ebc7bf5 broke compilation
for ldp board. The following patch fixes it. Also fixes a wrong
cast from a void __iomem * to u32.

Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>