powerpc: Remove an extraneous and incorrect declaration of pmac_nvram_init.

Signed-off-by: Paul Mackerras <paulus@samba.org>

include/asm-powerpc/nvram.h

@@ -68,7 +68,6 @@ extern int nvram_clear_error_log(void);
 extern struct nvram_partition *nvram_find_partition(int sig, const char *name);
 
 extern int pSeries_nvram_init(void);
-extern int pmac_nvram_init(void);
 extern int mmio_nvram_init(void);
 
 /* PowerMac specific nvram stuffs */