alpha: marvel: make use of raw_spinlock variants

The alpha/marvel code currently implements an irq_chip for handling
interrupts; due to how irq_chip handling is done, it's necessary for the
irq_chip methods to be invoked from hardirq context, even on a a
real-time kernel.  Because the spinlock_t type becomes a "sleeping"
spinlock w/ RT kernels, it is not suitable to be used with irq_chips.

A quick audit of the operations under the lock reveal that they do only
minimal, bounded work, and are therefore safe to do under a raw spinlock.

Signed-off-by: Julia Cartwright <julia@ni.com>
Signed-off-by: Matt Turner <mattst88@gmail.com>

arch/alpha/include/asm/core_marvel.h

@@ -312,7 +312,7 @@ struct io7 {
 	io7_port7_csrs *csrs;
 	struct io7_port ports[IO7_NUM_PORTS];
 
-	spinlock_t irq_lock;
+	raw_spinlock_t irq_lock;
 };
 
 #ifndef __EXTERN_INLINE

arch/alpha/kernel/core_marvel.c

@@ -118,7 +118,7 @@ alloc_io7(unsigned int pe)
 
 	io7 = alloc_bootmem(sizeof(*io7));
 	io7->pe = pe;
-	spin_lock_init(&io7->irq_lock);
+	raw_spin_lock_init(&io7->irq_lock);
 
 	for (h = 0; h < 4; h++) {
 		io7->ports[h].io7 = io7;

arch/alpha/kernel/sys_marvel.c

@@ -115,11 +115,11 @@ io7_enable_irq(struct irq_data *d)
 		return;
 	}
 
-	spin_lock(&io7->irq_lock);
+	raw_spin_lock(&io7->irq_lock);
 	*ctl |= 1UL << 24;
 	mb();
 	*ctl;
-	spin_unlock(&io7->irq_lock);
+	raw_spin_unlock(&io7->irq_lock);
 }
 
 static void
@@ -136,11 +136,11 @@ io7_disable_irq(struct irq_data *d)
 		return;
 	}
 
-	spin_lock(&io7->irq_lock);
+	raw_spin_lock(&io7->irq_lock);
 	*ctl &= ~(1UL << 24);
 	mb();
 	*ctl;
-	spin_unlock(&io7->irq_lock);
+	raw_spin_unlock(&io7->irq_lock);
 }
 
 static void
@@ -263,7 +263,7 @@ init_io7_irqs(struct io7 *io7,
 	 */
 	printk("  Interrupts reported to CPU at PE %u\n", boot_cpuid);
 
-	spin_lock(&io7->irq_lock);
+	raw_spin_lock(&io7->irq_lock);
 
 	/* set up the error irqs */
 	io7_redirect_irq(io7, &io7->csrs->HLT_CTL.csr, boot_cpuid);
@@ -295,7 +295,7 @@ init_io7_irqs(struct io7 *io7,
 	for (i = 0; i < 16; ++i)
 		init_one_io7_msi(io7, i, boot_cpuid);
 
-	spin_unlock(&io7->irq_lock);
+	raw_spin_unlock(&io7->irq_lock);
 }
 
 static void __init