soc: bcm: bcm2835-power: Refactor ASB control

The functions to control the async AXI bridges are almost identical.
So define a general function to handle it and keep the original ones as
wrapper. This should make this driver easier to extend.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Peter Robinson <pbrobinson@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220625113619.15944-9-stefan.wahren@i2se.com