Remove an obsolete TODO comment from several minidump implementations.

The comment referenced a non-existent function, and these minidump
implementations already buffer discontiguous physical data pages by
mapping them into a single VA range that gets passed to the dump device,
so there is no real advantage in batching calls to blk_write().

The RISC-V and MIPS minidump implementations still write a page at a
time and so would benefit from some form of batching.

MFC after:	2 weeks
Sponsored by:	Juniper Networks, Klara Inc.

sys/amd64/amd64/minidump_machdep.c

@@ -409,7 +409,6 @@ minidumpsys(struct dumperinfo *di)
 	}
 
 	/* Dump memory chunks */
-	/* XXX cluster it up and use blk_dump() */
 	for (i = 0; i < vm_page_dump_size / sizeof(*vm_page_dump); i++) {
 		bits = vm_page_dump[i];
 		while (bits) {

sys/arm64/arm64/minidump_machdep.c

@@ -374,7 +374,6 @@ minidumpsys(struct dumperinfo *di)
 	}
 
 	/* Dump memory chunks */
-	/* XXX cluster it up and use blk_dump() */
 	for (i = 0; i < vm_page_dump_size / sizeof(*vm_page_dump); i++) {
 		bits = vm_page_dump[i];
 		while (bits) {

sys/i386/i386/minidump_machdep_base.c

@@ -321,7 +321,6 @@ minidumpsys(struct dumperinfo *di)
 	}
 
 	/* Dump memory chunks */
-	/* XXX cluster it up and use blk_dump() */
 	for (i = 0; i < vm_page_dump_size / sizeof(*vm_page_dump); i++) {
 		bits = vm_page_dump[i];
 		while (bits) {

sys/powerpc/powerpc/minidump_machdep.c

@@ -381,7 +381,6 @@ minidumpsys(struct dumperinfo *di)
 	dump_total("pmap", pmapsize);
 
 	/* Dump memory chunks */
-	/* XXX cluster it up and use blk_dump() */
 	for (i = 0; i < vm_page_dump_size / sizeof(*vm_page_dump); i++) {
 		bits = vm_page_dump[i];
 		/* TODO optimize with bit manipulation instructions */