windcharger: replace all instances of "gfwc" with "gfmn"

b/23085458

Change-Id: Ic6541f512d5129ce3a6e0b7d5319b5698a7932e9
diff --git a/arch/mips/configs/gfwc100_defconfig b/arch/mips/configs/gfmn100_defconfig
similarity index 100%
rename from arch/mips/configs/gfwc100_defconfig
rename to arch/mips/configs/gfmn100_defconfig