hostap: add SAE_PWE_EARLY_EXIT Kconfig

In order to mitigate side channel attacks, even if the PWE is found the WPA
supplicant goes through full iterations, but in some low-resource systems
this can be intensive, so, add an option to exit early.
Note that this is highly insecure and shouldn't be used in production

Signed-off-by: Gang Li <gang.li_1@nxp.com>