[WATCHDOG] davinci: convert to ioremap() + io[read|write]

Remove davinci platform-specific IO accessor macros in favor
of standard ioremap + io[read|write]* functions.

Also, convert printk(KERN_ERR ....) into dev_err(...)

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>