x86: Drop stray subtarget "epia"

This subtarget was added by 961c0ea, probably by mistake.  It does
not contain anything beside a kernel config.

Acked-by: Daniel Golle <[email protected]>
Cc: Daniel Golle <[email protected]>
Signed-off-by: Baptiste Jonglez <[email protected]>

Author: Baptiste Jonglez