CONFIG_ARCH_MX503 is not available for the default architecture x86.
Result is shown for architecture arm
default or selected kernelversion does not have config value CONFIG_ARCH_MX503.
Result is shown for kernelversion 5.4.4

i.MX50 + i.MX53

configname: CONFIG_ARCH_MX503

Freescale CPU family:
└─> i.MX50 + i.MX53

This enables support for machines using Freescale's i.MX50 and i.MX51