watchdog: omap_wdt: Disable DM watchdog support in SPL

watchdog: omap_wdt: Disable DM watchdog support in SPL

This patch disables DM watchdog support for SPL builds and uses
the legacy omap watchdog driver on TI AM335x chipsets.

The following build error is reported if DM watchdog support was
enabled in SPL:

  CC      spl/drivers/usb/gadget/rndis.o
  LD      spl/drivers/usb/gadget/built-in.o
  LD      spl/drivers/usb/musb-new/built-in.o
  LD      spl/drivers/built-in.o
  LD      spl/u-boot-spl
arm-linux-ld.bfd: u-boot-spl section .u_boot_list will not fit in region .sram
arm-linux-ld.bfd: region .sram overflowed by 440 bytes
make[1]: *** [spl/u-boot-spl] Error 1
make: *** [spl/u-boot-spl] Error 2

Adjusted WATCHDOG_RESET macro accordingly. Earlier it was pointing
to hw_watchdog_reset. Since CONFIG_WATCHDOG replaces CONFIG_HW_WATCHDOG,
now WATCHDOG_RESET macro points to watchdog_reset. This watchdog_reset
is not defined anywhere for am33xx/omap2 and needs to be defined. Fixed
this by simply calling hw_watchdog_reset in watchdog_reset.

Built and tested on AM335x device (BeagleboneBlack), compile tested for
all other AM33xx/omap2 based boards.

Signed-off-by: Suniel Mahesh <sunil.m@techveda.org>
[trini: Fix watchdog.h logic]
Signed-off-by: Tom Rini <trini@konsulko.com>