powerpc/32s: Remove m8260_gorom()

Last user of m8260_gorom() was removed by
Commit 917f0af9 ("powerpc: Remove arch/ppc and include/asm-ppc")
removed last user of m8260_gorom().

In fact m8260_gorom() was ported to arch/powerpc/ but the
platform using it died with arch/ppc/

Remove it.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/13f7532f21df3196e8c78b4f82a9c8d5487aca35.1620292185.git.christophe.leroy@csgroup.eu

arch/powerpc/kernel/head_book3s_32.S

@@ -1256,42 +1256,6 @@ setup_usbgecko_bat:
 	blr
 #endif
 
-#ifdef CONFIG_8260
-/* Jump into the system reset for the rom.
- * We first disable the MMU, and then jump to the ROM reset address.
- *
- * r3 is the board info structure, r4 is the location for starting.
- * I use this for building a small kernel that can load other kernels,
- * rather than trying to write or rely on a rom monitor that can tftp load.
- */
-       .globl  m8260_gorom
-m8260_gorom:
-	mfmsr	r0
-	rlwinm	r0,r0,0,17,15	/* clear MSR_EE in r0 */
-	sync
-	mtmsr	r0
-	sync
-	mfspr	r11, SPRN_HID0
-	lis	r10, 0
-	ori	r10,r10,HID0_ICE|HID0_DCE
-	andc	r11, r11, r10
-	mtspr	SPRN_HID0, r11
-	isync
-	li	r5, MSR_ME|MSR_RI
-	lis	r6,2f@h
-	addis	r6,r6,-KERNELBASE@h
-	ori	r6,r6,2f@l
-	mtspr	SPRN_SRR0,r6
-	mtspr	SPRN_SRR1,r5
-	isync
-	sync
-	rfi
-2:
-	mtlr	r4
-	blr
-#endif
-
-
 /*
  * We put a few things here that have to be page-aligned.
  * This stuff goes at the beginning of the data segment,