Finish converting CONFIG_WATCHDOG, HW_WATCHDOG and WDT to Kconfig

Because of how these symbols work, and the remaining board config.h file
uses, we need to do these at the same time.  In some cases we just get
to move rather directly to the defconfigs.  A few cases require manual
intervention.

For the case of the eb_cpu5282 we need to select HW_WATCHDOG for the
target, given how it's implemented.

For the cases of m53menlo, dh_imx6, display5, and display5_factory we
disable SPL watchdog support as the particular combination of options
they want would require either more symbols or enabling SPL_DM.

Signed-off-by: Tom Rini <trini@konsulko.com>