[POWERPC] Rename MPIC_BROKEN_U3 to MPIC_U3_HT_IRQS

Rename MPIC_BROKEN_U3 to something a little more descriptive. Its
effect is to enable support for HT irqs behind the PCI-X/HT bridge on
U3/U4 (aka. CPC9x5) parts.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/platforms/Kconfig b/arch/powerpc/platforms/Kconfig
index 86be82a..ac62fa0 100644
--- a/arch/powerpc/platforms/Kconfig
+++ b/arch/powerpc/platforms/Kconfig
@@ -115,7 +115,7 @@
 	bool
 	default n
 
-config MPIC_BROKEN_U3
+config MPIC_U3_HT_IRQS
 	bool
 	depends on PPC_MAPLE
 	default y