ata: ahci_brcm: Fix use of BCM7216 reset controller

ata: ahci_brcm: Fix use of BCM7216 reset controller

This driver may use one of two resets controllers.  Keep them in separate
variables to keep things simple.  The reset controller "rescal" is shared
between the AHCI driver and the PCIe driver for the BrcmSTB 7216 chip.  Use
devm_reset_control_get_optional_shared() to handle this sharing.

[bhelgaas: add Jens' ack from v5 posting]
Fixes: 272ecd60a636 ("ata: ahci_brcm: BCM7216 reset is self de-asserting")
Fixes: c345ec6a50e9 ("ata: ahci_brcm: Support BCM7216 reset controller name")
Link: https://lore.kernel.org/r/20210430152156.21162-3-jim2101024@gmail.com
Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>