ata: sata_dwc_460ex: fix clear_interrupt_bit() clearing all pending interrupts

ata: sata_dwc_460ex: fix clear_interrupt_bit() clearing all pending interrupts

clear_interrupt_bit() ignores the bit argument and performs a
read-write-back of the entire INTPR register.  If INTPR uses standard
Write-1-to-Clear semantics, this clears every pending interrupt bit,
not just the intended one.  Coalesced interrupts (e.g. DMAT + NEWFP)
would be cleared together, silently losing the second event.

Write only the specific bit to clear so that other pending interrupts
are preserved.

Fixes: 62936009f35a ("[libata] Add 460EX on-chip SATA driver, sata_dwc_460ex")
Assisted-by: opencode:big-pickle
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>