Input: ipaq-micro-keys - fix potential deadlock

Input: ipaq-micro-keys - fix potential deadlock

The driver acquires the micro->lock spinlock in process context (in
micro_key_start() and micro_key_stop()) without disabling interrupts.
However, this lock is also acquired in hardirq context by the MFD core
rx handler (micro_rx_msg()) which is called from the serial ISR.

This can lead to a lock inversion deadlock if the interrupt fires on the
same CPU while the process context holds the lock.

Fix this by using guard(spinlock_irq) instead of guard(spinlock) in
micro_key_start() and micro_key_stop() to disable interrupts while
holding the lock.

Reported-by: sashiko-bot@kernel.org
Assisted-by: Antigravity:gemini-3.5-flash
Link: https://patch.msgid.link/aij-pfaKK-Nna7wf@google.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>