alpha: Replace strncmp with str_has_prefix

In commit b6b27355
("tracing: Use str_has_prefix() instead of using fixed sizes")
the newly introduced str_has_prefix() was used
to replace error-prone strncmp(str, const, len).
Here fix codes with the same pattern.
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Signed-off-by: Matt Turner <mattst88@gmail.com>

arch/alpha/boot/tools/objstrip.c

@@ -148,7 +148,7 @@ main (int argc, char *argv[])
 #ifdef __ELF__
     elf = (struct elfhdr *) buf;
 
-    if (elf->e_ident[0] == 0x7f && strncmp((char *)elf->e_ident + 1, "ELF", 3) == 0) {
+    if (elf->e_ident[0] == 0x7f && str_has_prefix((char *)elf->e_ident + 1, "ELF")) {
 	if (elf->e_type != ET_EXEC) {
 	    fprintf(stderr, "%s: %s is not an ELF executable\n",
 		    prog_name, inname);

arch/alpha/kernel/setup.c

@@ -474,7 +474,7 @@ setup_arch(char **cmdline_p)
 #ifndef alpha_using_srm
 	/* Assume that we've booted from SRM if we haven't booted from MILO.
 	   Detect the later by looking for "MILO" in the system serial nr.  */
-	alpha_using_srm = strncmp((const char *)hwrpb->ssn, "MILO", 4) != 0;
+	alpha_using_srm = !str_has_prefix((const char *)hwrpb->ssn, "MILO");
 #endif
 #ifndef alpha_using_qemu
 	/* Similarly, look for QEMU.  */