rtc: omap: clean up probe error handling

rtc: omap: clean up probe error handling

Remove some debug messages and return errors from subsystems rather than
always fail with -EIO.

Note that the class-registration error has already been logged by rtc
core.

Signed-off-by: Johan Hovold <[email protected]>
Cc: Alessandro Zummo <[email protected]>
Cc: Tony Lindgren <[email protected]>
Cc: Benot Cousson <[email protected]>
Cc: Lokesh Vutla <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: Sekhar Nori <[email protected]>
Cc: Tero Kristo <[email protected]>
Cc: Keerthy J <[email protected]>
Tested-by: Felipe Balbi <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>