MIPS: dec: prom: Remove unused unregister_prom_console() declaration

The unregister_prom_console() has been removed since
commit 36a8853 ("[MIPS] Fix and cleanup the mess that a dozen
prom_printf variants are."), so remove it.

Signed-off-by: Gaosheng Cui <[email protected]>
Acked-by: Maciej W. Rozycki <[email protected]>
Signed-off-by: Thomas Bogendoerfer <[email protected]>

Author: gscui

arch/mips/include/asm/dec/prom.h

@@ -160,6 +160,5 @@ extern void prom_identify_arch(u32);
 extern void prom_init_cmdline(s32, s32 *, u32);
 
 extern void register_prom_console(void);
-extern void unregister_prom_console(void);
 
 #endif /* _ASM_DEC_PROM_H */