Move sequence of masking and unmasking global interrupts from buttress
interrupt handler to generic one that handles both VPUIP and BTRS
interrupts.

Unmasking global interrupts will re-trigger MSI for any pending interrupts.
Lack of this sequence can randomly cause to miss any VPUIP interrupt that
comes after reading VPU_40XX_HOST_SS_ICB_STATUS_0 and before clearing
all active interrupt sources.

Fixes: 79cdc56c ("accel/ivpu: Add initial support for VPU 4")
Signed-off-by: Karol Wachowski <karol.wachowski@linux.intel.com>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230925121137.872158-6-stanislaw.gruszka@linux.intel.com