mambo: Update P9 PVR to reflect Scale out 24 core chips

The P9 PVR bits 48:51 don't indicate a revision but instead different
configurations.  From BookIV we have:
 Bits:  Configuration
    0:  Scale out 12 cores
    1:  Scale out 24 cores
    2:  Scale up 12 cores
    3:  Scale up 24 cores

Skiboot will mostly the use "Scale out 24 core" configuration
(ie. SMT4 not SMT8) so reflect this in mambo.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

external/mambo/skiboot.tcl

@@ -82,8 +82,8 @@ if { $default_config == "PEGASUS" } {
     myconf config processor/initial/PVR 0x4b0201
 }
 if { $default_config == "P9" } {
-    # make sure we look like a POWER9 DD2
-    myconf config processor/initial/PVR 0x4e0200
+    # PVR configured for POWER9 DD2.0 Scale out 24 Core (ie SMT4)
+    myconf config processor/initial/PVR 0x4e1200
     myconf config processor/initial/SIM_CTRL1 0xc228000400000000
 }
 if { [info exists env(SKIBOOT_SIMCONF)] } {