CONFIG_HPDCA is not available for thedefaultarchitecture x86.
Result is shown for architecture m68k

HP DCA serial support

configname: CONFIG_HPDCA

Linux Kernel Configuration
└─>Character devices
└─>HP DCA serial support
In linux kernel since version 2.6.12  
If you want to use the internal "DCA" serial ports on an HP300
machine, say Y here.