MIPS: MSP71xx: Remove dead CONFIG_MTD_PMC_MSP_RAMROOT

CONFIG_MTD_PMC_MSP_RAMROOT doesn't exist in Kconfig, therefore removing all
references for it from the source code.
Signed-off-by: Christoph Egger <siccegge@cs.fau.de>
To:     Ralf Baechle <ralf@linux-mips.org>,
        Yoichi Yuasa <yuasa@linux-mips.org>, linux-mips@linux-mips.org,
        linux-kernel@vger.kernel.org
Cc:     vamos@i4.informatik.uni-erlangen.de
Acked-by: Shane McDonald <mcdonald.shane@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/1375/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/pmc-sierra/msp71xx/msp_prom.h

@@ -124,10 +124,6 @@ extern void prom_meminit(void);
 extern void prom_fixup_mem_map(unsigned long start_mem,
 			       unsigned long end_mem);
 
-#ifdef CONFIG_MTD_PMC_MSP_RAMROOT
-extern bool get_ramroot(void **start, unsigned long *size);
-#endif
-
 extern int get_ethernet_addr(char *ethaddr_name, char *ethernet_addr);
 extern unsigned long get_deviceid(void);
 extern char identify_enet(unsigned long interface_num);