net: watchdog: rename __dev_watchdog_up() and dev_watchdog_down()

net: watchdog: rename __dev_watchdog_up() and dev_watchdog_down()

In commit d7811e623dd4 ("[NET]: Drop tx lock in dev_watchdog_up")
dev_watchdog_up() became a simple wrapper for __netdev_watchdog_up()

Herbert also said : "In 2.6.19 we can eliminate the unnecessary
__dev_watchdog_up and replace it with dev_watchdog_up."

This patch consolidates things to have only two functions, with
a common prefix.

- netdev_watchdog_up(), exported for the sake of one freescale driver.
  This replaces __netdev_watchdog_up() and dev_watchdog_up().

- netdev_watchdog_down(), static to net/sched/sch_generic.c
  This replaces dev_watchdog_down().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Link: https://patch.msgid.link/20250105090924.1661822-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>