mach-omap2: Remove use of deprecated marco, PTR_RET in devices.c

This removes the deprecacted marco, PTR_RET and changes the
functions that use this marco in their return statement to
instead use the non deprecacted function, PTR_ERR_OR_ZERO
for the file devices.c.

Signed-off-by: Nicholas Krause <xerofoify@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>