dma-mapping: fix filename references

After commit cf65a0f6 ("dma-mapping: move all DMA mapping code to
kernel/dma") some of the files are referring to outdated information,
i.e. old file names of DMA mapping sources. Fix it here.

Note, the lines with "Glue code for..." have been removed completely.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

Documentation/x86/x86_64/boot-options.rst

@@ -230,7 +230,7 @@ IOMMU (input/output memory management unit)
 ===========================================
 Multiple x86-64 PCI-DMA mapping implementations exist, for example:
 
-   1. <lib/dma-direct.c>: use no hardware/software IOMMU at all
+   1. <kernel/dma/direct.c>: use no hardware/software IOMMU at all
       (e.g. because you have < 3 GB memory).
       Kernel boot message: "PCI-DMA: Disabling IOMMU"
 

arch/ia64/kernel/setup.c

@@ -256,7 +256,7 @@ __initcall(register_memory);
  * This function checks if the reserved crashkernel is allowed on the specific
  * IA64 machine flavour. Machines without an IO TLB use swiotlb and require
  * some memory below 4 GB (i.e. in 32 bit area), see the implementation of
- * lib/swiotlb.c. The hpzx1 architecture has an IO TLB but cannot use that
+ * kernel/dma/swiotlb.c. The hpzx1 architecture has an IO TLB but cannot use that
  * in kdump case. See the comment in sba_init() in sba_iommu.c.
  *
  * So, the only machvec that really supports loading the kdump kernel

arch/x86/kernel/pci-swiotlb.c

 // SPDX-License-Identifier: GPL-2.0
-/* Glue code to lib/swiotlb.c */
 
 #include <linux/pci.h>
 #include <linux/cache.h>

arch/x86/kernel/setup.c

@@ -486,7 +486,7 @@ static int __init reserve_crashkernel_low(void)
 	ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size, &base);
 	if (ret) {
 		/*
-		 * two parts from lib/swiotlb.c:
+		 * two parts from kernel/dma/swiotlb.c:
 		 * -swiotlb size: user-specified with swiotlb= or default.
 		 *
 		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it

arch/x86/pci/sta2x11-fixup.c

 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * arch/x86/pci/sta2x11-fixup.c
- * glue code for lib/swiotlb.c and DMA translation between STA2x11
- * AMBA memory mapping and the X86 memory mapping
+ * DMA translation between STA2x11 AMBA memory mapping and the x86 memory mapping
  *
  * ST Microelectronics ConneXt (STA2X11/STA2X10)
  *