CONFIG_HP300 is not available for thedefaultarchitecture x86.
Result is shown for architecture m68k

HP9000/300 and HP9000/400 support

configname: CONFIG_HP300

Linux/68k Kernel Configuration
└─>Platform dependent setup
└─>HP9000/300 and HP9000/400 support
In linux kernel since version 2.6.12  
This option enables support for the HP9000/300 and HP9000/400 series
of workstations. Support for these machines is still somewhat
experimental. If you plan to try to use the kernel on such a machine
say Y here.
Everybody else says N.

selects

CONFIG_MMU_MOTOROLA
CONFIG_LEGACY_TIMER_TICK

depends
NOT CONFIG_MMU_SUN3 or CONFIG_M68KCLASSIC or &

is selected by
CONFIG_KEYBOARD_HIL