Convert CONFIG_SYS_FLASH_ERASE_TOUT et al to Kconfig

Convert CONFIG_SYS_FLASH_ERASE_TOUT et al to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_FLASH_ERASE_TOUT
   CONFIG_SYS_FLASH_LOCK_TOUT
   CONFIG_SYS_FLASH_UNLOCK_TOUT
   CONFIG_SYS_FLASH_WRITE_TOUT

In practice, for two m68k platforms we move to hard-coding with a
comment the timeout values, rather than try and make convoluted Kconfig
logic.  We add options for the write and erase options to the pic32
flash driver, as this driver does make use of them.  Everywhere else
these are unreferenced values.

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