linuxkpi: Fix set_memory_*

[tijl]

Summary

set_memory_* is currently implemented using PHYS_TO_DMAP but not all
architectures have a DMAP. Looking at how this function is used the
given address isn't physical, but virtual so the PHYS_TO_DMAP call
can simply be removed.

Also cast numpages before shifting it to avoid overflow.

[tijl]

Example use:
https://github.com/freebsd/drm-kmod/blob/1f0859f54b6f4bcce3862f30c9c1b5cfd08710db/drivers/gpu/drm/radeon/radeon_gart.c#L83
set_memory_uc called on ptr returned by linuxkpi dma_alloc_coherent, which returns a virtual address.

sys/compat/linuxkpi/common/include/asm/set_memory.h

main(int argc, char *argv[])
         int ch;
 
         while ((ch = getopt(argc, argv, "ad:f:hos")) != -1) {
                 switch (ch) {
                 case 'a':
                         aflag = 1;
                         break;
                 case 'd':
+                        if (strncmp(optarg, "pcm", 3) == 0)
+                                optarg += 3;
                         errno = 0;
                         dunit = strtol(optarg, NULL, 10);
                         if (errno == EINVAL || errno == ERANGE)
                                 err(1, "strtol(%s)", optarg);
                         dflag = 1;
                         break;
                 case 'f':
                         name = optarg;
next:
         (void)mixer_close(m);
 
         return (0);
 }
 
 static void __dead2
 usage(void)
 {
-        fprintf(stderr, "usage: %1$s [-f device] [-d unit] [-os] [dev[.control[=value]]] ...\n"
-            "       %1$s [-d unit] [-os] -a\n"
+        fprintf(stderr, "usage: %1$s [-f device] [-d pcmN | N] [-os] [dev[.control[=value]]] ...\n"
+            "       %1$s [-os] -a\n"
             "       %1$s -h\n", getprogname());
         exit(1);
 }
 
 static void
 initctls(struct mixer *m)
 {
         struct mix_dev *dp;