drivers: qcom: rpmh: Use spin_lock_irqX variants

The spinlock in mbox_ctrlr may be accessed in an IRQ context when the
interrupt response tasklet calls tx_done callback while another process
is calling rpmh-write to send message to the controller.

BUG: spinlock recursion on CPU#0, kworker/u16:2/282
lock: mbox_ctrlr+0x18/0x90, .magic: dead4ead, .owner:
kworker/u16:2/282, .owner_cpu: 0
Causing a watchdog bite!
Call trace:
	dump_backtrace+0x0/0x200
	show_stack+0x20/0x28
	dump_stack+0xb0/0xec
	spin_bug+0x90/0xb4
	do_raw_spin_lock+0xcc/0x1bc
	_raw_spin_lock+0x28/0x34
	rpmh_tx_done+0xa0/0xf0
	tx_tick+0x64/0x88
	mbox_chan_txdone+0x30/0x5c
	tcs_notify_tx_done+0x68/0x114
	tasklet_action+0x70/0x104
	__do_softirq+0x114/0x3e8
	irq_exit+0xd0/0xfc
	__handle_domain_irq+0x70/0xbc
	gic_handle_irq+0xdc/0x1c0

when called from -

	el1_irq+0xb4/0x12c
	__slab_alloc.isra.69.constprop.71+0x58/0x80
	kmem_cache_alloc_trace+0x288/0x2b0
	__rpmh_write+0xcc/0x22c
	rpmh_write+0x138/0x1e4
	rpmh_regulator_send_aggregate_requests+0x238/0x510
	rpmh_regulator_vrm_set_mode_index+0x5c/0xc0
	rpmh_regulator_vrm_set_load+0x7c/0x88
	drms_uA_update+0xa4/0x308
	regulator_enable+0xec/0x19c
	regulator_enable+0x38/0x19c
	pdphy_enable_power.isra.2+0xe8/0x1d8
	pd_phy_open+0x84/0x1cc
	usbpd_set_state+0x340/0x9c0
	usbpd_sm+0x5d8/0x1690
	process_one_work+0x15c/0x440
	worker_thread+0x60/0x448
	kthread+0xec/0x100
	ret_from_fork+0x10/0x40

Change-Id: I4b1ddcb06cbd11675eab7e2c84635f3643d50dcd
Signed-off-by: Lina Iyer <ilina@codeaurora.org>