MIPS: r4kcache: Add EVA case for protected_writeback_dcache_line

Commit de8974e3f76c0 ("MIPS: asm: r4kcache: Add EVA cache flushing
functions") added cache function for EVA using the cachee instruction.
However, it didn't add a case for the protected_writeback_dcache_line.
mips_dsemul() calls r4k_flush_cache_sigtramp() which in turn uses
the protected_writeback_dcache_line() to flush the trampoline code
back to memory. This used the wrong "cache" instruction leading to
random userland crashes on non-FPU cores.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: <stable@vger.kernel.org> # v3.15+
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/8331/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/r4kcache.h

@@ -257,7 +257,11 @@ static inline void protected_flush_icache_line(unsigned long addr)
  */
 static inline void protected_writeback_dcache_line(unsigned long addr)
 {
+#ifdef CONFIG_EVA
+	protected_cachee_op(Hit_Writeback_Inv_D, addr);
+#else
 	protected_cache_op(Hit_Writeback_Inv_D, addr);
+#endif
 }
 
 static inline void protected_writeback_scache_line(unsigned long addr)