MIPS: Replace add and sub instructions in relocate_kernel.S with addiu

Fixes the assembler errors generated when compiling a MIPS R6 kernel with
CONFIG_KEXEC on, by replacing the offending add and sub instructions with
addiu instructions.

Build errors:
arch/mips/kernel/relocate_kernel.S: Assembler messages:
arch/mips/kernel/relocate_kernel.S:27: Error: invalid operands `dadd $16,$16,8'
arch/mips/kernel/relocate_kernel.S:64: Error: invalid operands `dadd $20,$20,8'
arch/mips/kernel/relocate_kernel.S:65: Error: invalid operands `dadd $18,$18,8'
arch/mips/kernel/relocate_kernel.S:66: Error: invalid operands `dsub $22,$22,1'
scripts/Makefile.build:294: recipe for target 'arch/mips/kernel/relocate_kernel.o' failed

Signed-off-by: James Cowgill <James.Cowgill@imgtec.com>
Cc: <stable@vger.kernel.org> # 4.0+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10558/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/relocate_kernel.S

@@ -24,7 +24,7 @@ LEAF(relocate_new_kernel)
 
 process_entry:
 	PTR_L		s2, (s0)
-	PTR_ADD		s0, s0, SZREG
+	PTR_ADDIU	s0, s0, SZREG
 
 	/*
 	 * In case of a kdump/crash kernel, the indirection page is not
@@ -61,9 +61,9 @@ copy_word:
 	/* copy page word by word */
 	REG_L		s5, (s2)
 	REG_S		s5, (s4)
-	PTR_ADD		s4, s4, SZREG
-	PTR_ADD		s2, s2, SZREG
-	LONG_SUB	s6, s6, 1
+	PTR_ADDIU	s4, s4, SZREG
+	PTR_ADDIU	s2, s2, SZREG
+	LONG_ADDIU	s6, s6, -1
 	beq		s6, zero, process_entry
 	b		copy_word
 	b		process_entry