bitbake.conf: Simplify FILESPATH

bitbake.conf: Simplify FILESPATH

Files are very rarely, if ever placed in ${PF}. If a recipe needs to do this,
it can easily append to FILESPATH so it makes sense to drop this from the
default search path.

Equally, using FILE_DIR as part of the search path leads to 'bad' SRC_URI
entries and/or file layouts which are not preferred. I'm therefore of the
opinion we should also remove this from FILESPATH and encourage people to
cleanup any places this breaks my correcting the layouts to match the standard
or worst case adding to FILESPATH in recipes that need it.

These changes work towards making the system more friendly as users won't be
greeted with huge search paths we rearely use making the "correct" layout
more obvious.

(From OE-Core rev: 3efa13cd76bbd5611805021945fc9def88d9fd93)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>