MIPS: mips-r2-to-r6-emul.h: Inline empty `mipsr2_decoder'

Use `static inline' rather than `static __maybe_unused' for
`mipsr2_decoder' in the empty case, making inlining explicit where it
will happen anyway.
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9678/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/mips-r2-to-r6-emul.h

@@ -84,7 +84,7 @@ extern void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
 
 #ifndef CONFIG_MIPSR2_TO_R6_EMULATOR
 static int mipsr2_emulation;
-static __maybe_unused int mipsr2_decoder(struct pt_regs *regs, u32 inst) { return 0; };
+static inline int mipsr2_decoder(struct pt_regs *regs, u32 inst) { return 0; };
 #else
 /* MIPS R2 Emulator ON/OFF */
 extern int mipsr2_emulation;