KVM: selftests: Fix spelling mistake "probabalistic" -> "probabilistic"

There is a spelling mistake in some help text. Fix it.
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Message-Id: <20221201091354.1613652-1-colin.i.king@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/dirty_log_perf_test.c

@@ -398,7 +398,7 @@ static void help(char *name)
 	printf(" -x: Split the memory region into this number of memslots.\n"
 	       "     (default: 1)\n");
 	printf(" -w: specify the percentage of pages which should be written to\n"
-	       "     as an integer from 0-100 inclusive. This is probabalistic,\n"
+	       "     as an integer from 0-100 inclusive. This is probabilistic,\n"
 	       "     so -w X means each page has an X%% chance of writing\n"
 	       "     and a (100-X)%% chance of reading.\n"
 	       "     (default: 100 i.e. all pages are written to.)\n");