nxp: Rename board/freescale/common/Kconfig to arch/Kconfig.nxp

Now that board/freescale/common/Kconfig is safe to be included once,
globally, rename this to arch/Kconfig.nxp to better reflect that it
contains options that are valid on multiple architectures and SoC
families, and not specific to NXP reference platforms either.

Cc: Stefano Babic <sbabic@denx.de>
Cc: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/Kconfig b/arch/Kconfig
index 1ad61ab..6495e78 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -451,7 +451,12 @@
 source "arch/xtensa/Kconfig"
 source "arch/riscv/Kconfig"
 
-source "board/freescale/common/Kconfig"
+if ARM || M68K || PPC
+
+source "arch/Kconfig.nxp"
+
+endif
+
 source "board/keymile/Kconfig"
 
 if MIPS || MICROBLAZE