hw/ppc/spapr: Fix error message when firmware could not be loaded

When specifying a non-existing file with the "-bios" parameter, QEMU
complained that it "could not find LPAR rtas". That's obviously a
copy-n-paste bug from the code which loads the spapr-rtas.bin, it
should complain about a missing firmware file instead.
Additionally the error message was printed with hw_error() - which
also dumps the whole CPU state. However, this does not make much
sense here since the CPU is not running yet and thus the registers
only contain zeroes. So let's use error_report() here instead.
And while we're at it, let's also bail out if the firmware file
had zero length.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>

hw/ppc/spapr.c

@@ -1641,12 +1641,12 @@ static void ppc_spapr_init(MachineState *machine)
     }
     filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
     if (!filename) {
-        hw_error("Could not find LPAR rtas '%s'\n", bios_name);
+        error_report("Could not find LPAR firmware '%s'", bios_name);
         exit(1);
     }
     fw_size = load_image_targphys(filename, 0, FW_MAX_SIZE);
-    if (fw_size < 0) {
-        hw_error("qemu: could not load LPAR rtas '%s'\n", filename);
+    if (fw_size <= 0) {
+        error_report("Could not load LPAR firmware '%s'", filename);
         exit(1);
     }
     g_free(filename);