spi: dw: fix race between IRQ handler and error handler on SMP

spi: dw: fix race between IRQ handler and error handler on SMP

On SMP systems, dw_spi_handle_err() can be called from the SPI core
kthread while the IRQ handler is still accessing the FIFO on another
CPU. Resetting the chip via dw_spi_reset_chip() during an active FIFO
read/write causes a bus error.

Fix this by calling disable_irq() before the chip reset, which masks
the IRQ and waits for any in-flight handler to complete via
synchronize_irq(). This ensures no handler is accessing the FIFO when
the reset occurs.

Signed-off-by: Peng Yang <pyangyyd@amazon.com>
Suggested-by: Jonathan Chocron <jonnyc@amazon.com>
Link: https://patch.msgid.link/20260608095849.3446-1-pyangyyd@amazon.com
Signed-off-by: Mark Brown <broonie@kernel.org>