devicetree: Remove lpc interrupt properties

After commit 7b12d54 ("hw/lpc: Configure SerIRQ interrupts on
P9P"), we abort on p9p Simics:

[ 1486.000029845,3] Duplicate property "interrupt-map" in node /lpcm-opb@6030000000000/lpc@f0000000
[ 1487.000158147,0] Aborting!
CPU 0000 Backtrace:
 S: 0000000031c13940 R: 0000000030013d18   .backtrace+0x5c
 S: 0000000031c139f0 R: 000000003001dbf8   ._abort+0x60
 S: 0000000031c13a80 R: 000000003002d448   .new_property+0x94
 S: 0000000031c13b20 R: 000000003002d5e8   .dt_add_property+0xd0
 S: 0000000031c13bc0 R: 000000003004202c   .lpc_create_int_map+0xa4
 S: 0000000031c13da0 R: 0000000030043748   .lpc_finalize_interrupts+0x94
 S: 0000000031c13e30 R: 0000000030015d18   .main_cpu_entry+0x620
 S: 0000000031c13f00 R: 0000000030002740   boot_entry+0x1b8

Since skiboot creates these interrupt properties now, and always has on
older p9 systems, remove them from the input device tree.

Signed-off-by: Reza Arbab <arbab@linux.ibm.com>
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>

external/devicetree/p9.dts

@@ -140,7 +140,7 @@
 			compatible = "ibm,power9-xive-x";
 		};
 
-		PSI_X0: psihb@5012900 {
+		psihb@5012900 {
 			reg = <0x5012900 0x100>;
 			compatible = "ibm,power9-psihb-x", "ibm,psihb-x";
 
@@ -192,20 +192,6 @@
 				  0x0 0x0 0xe0000000 0x10000000 /* MEM space */
 				  0x1 0x0 0xd0010000 0x00010000 /* IO space */ >;
 
-			/*
-			 * We currently only support level interrupts on the LPC,
-			 * we use 1 cell.
-			 */
-			#interrupt-cells = <0x1>;
-
-			/*
-			 * Route the LPC interrupts to one of the 4 supported
-			 * PSI interrupt inputs [7...10].
-			 */
-			interrupt-map = <0x0 0x0 0x4 &PSI_X0 0x8
-					 0x0 0x0 0xa &PSI_X0 0x9>;
-			interrupt-map-mask = <0x0 0x0 0xff>;
-
 			/* Devices on the LPC bus go here */
 
 			serial@i3f8 {