x86 iommu: add more documentation

Fix coding style in pci-dma_64.c and add stubs for documentation. I
hope someone fills the rest, I understand maybe off and soft...
Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Documentation/kernel-parameters.txt

@@ -812,6 +812,19 @@ and is between 256 and 4096 characters. It is defined in the file
 
 	inttest=	[IA64]
 
+	iommu=		[x86]
+		off
+		force
+		noforce
+		biomerge
+		panic
+		nopanic
+		merge
+		nomerge
+		forcesac
+		soft
+
+
 	intel_iommu=	[DMAR] Intel IOMMU driver (DMAR) option
 		off
 			Disable intel iommu driver.

arch/x86/kernel/pci-dma_64.c

@@ -232,32 +232,32 @@ static __init int iommu_setup(char *p)
 		return -EINVAL;
 
 	while (*p) {
-		if (!strncmp(p,"off",3))
+		if (!strncmp(p, "off", 3))
 			no_iommu = 1;
 		/* gart_parse_options has more force support */
-		if (!strncmp(p,"force",5))
+		if (!strncmp(p, "force", 5))
 			force_iommu = 1;
-		if (!strncmp(p,"noforce",7)) {
+		if (!strncmp(p, "noforce", 7)) {
 			iommu_merge = 0;
 			force_iommu = 0;
 		}
 
-		if (!strncmp(p, "biomerge",8)) {
+		if (!strncmp(p, "biomerge", 8)) {
 			iommu_bio_merge = 4096;
 			iommu_merge = 1;
 			force_iommu = 1;
 		}
-		if (!strncmp(p, "panic",5))
+		if (!strncmp(p, "panic", 5))
 			panic_on_overflow = 1;
-		if (!strncmp(p, "nopanic",7))
+		if (!strncmp(p, "nopanic", 7))
 			panic_on_overflow = 0;
-		if (!strncmp(p, "merge",5)) {
+		if (!strncmp(p, "merge", 5)) {
 			iommu_merge = 1;
 			force_iommu = 1;
 		}
-		if (!strncmp(p, "nomerge",7))
+		if (!strncmp(p, "nomerge", 7))
 			iommu_merge = 0;
-		if (!strncmp(p, "forcesac",8))
+		if (!strncmp(p, "forcesac", 8))
 			iommu_sac_force = 1;
 		if (!strncmp(p, "allowdac", 8))
 			forbid_dac = 0;
@@ -265,7 +265,7 @@ static __init int iommu_setup(char *p)
 			forbid_dac = -1;
 
 #ifdef CONFIG_SWIOTLB
-		if (!strncmp(p, "soft",4))
+		if (!strncmp(p, "soft", 4))
 			swiotlb = 1;
 #endif