MIPS: Loongson: Merge load addresses

Systems based upon the Loongson 1B & 1C CPUs share the same load
address, as do those based upon Loongson 1A. Unify the definition of
this load address to reduce duplication & avoid the need for an extra
Loongson 1A case in future.

[paul.burton@mips.com: Rewrite commit message.]
Signed-off-by: 谢致邦 (XIE Zhibang) <Yeking@Red54.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/14927/
Cc: linux-mips@linux-mips.org

arch/mips/loongson32/Platform

 cflags-$(CONFIG_CPU_LOONGSON1)		+= -march=mips32 -Wa,--trap
 platform-$(CONFIG_MACH_LOONGSON32)	+= loongson32/
 cflags-$(CONFIG_MACH_LOONGSON32)	+= -I$(srctree)/arch/mips/include/asm/mach-loongson32
-load-$(CONFIG_LOONGSON1_LS1B)		+= 0xffffffff80100000
-load-$(CONFIG_LOONGSON1_LS1C)		+= 0xffffffff80100000
+load-$(CONFIG_CPU_LOONGSON1)		+= 0xffffffff80100000