amba: reorder functions

Put helpers (here: amba_get_enable_pclk and amba_put_disable_pclk) at
the top of the file and then define callbacks directly before the
structs they are used in; in the same order.

Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20210126165835.687514-3-u.kleine-koenig@pengutronix.de


Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>