MIPS: Loongson64: Use three arguments for slti

LLVM's integrated assembler does not support 'slti <reg>, <imm>':

<instantiation>:16:12: error: invalid operand for instruction
 slti $12, (0x6300 | 0x0008)
           ^
arch/mips/kernel/head.S:86:2: note: while in macro instantiation
 kernel_entry_setup # cpu specific setup
 ^
<instantiation>:16:12: error: invalid operand for instruction
 slti $12, (0x6300 | 0x0008)
           ^
arch/mips/kernel/head.S:150:2: note: while in macro instantiation
 smp_slave_setup
 ^

To increase compatibility with LLVM's integrated assembler, use the full
form of 'slti <reg>, <reg>, <imm>', which matches the rest of
arch/mips/. This does not result in any change for GNU as.

Link: https://github.com/ClangBuiltLinux/linux/issues/1526


Reported-by: Ryutaroh Matsumoto <ryutaroh@ict.e.titech.ac.jp>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>