kernel.bbclass: avoid config changes based on the availability of pahole

kernel.bbclass: avoid config changes based on the availability of pahole

CONFIG_PAHOLE_HAS_SPLIT_BTF shows up in the config only when pahole is
installed on the host system. As a result, the config changes depending on
whether pahole is installed or not.

Set PAHOLE=false to ensure that it is never found.

If this is actually needed in the future, then we can add an option for
it and create a host package for pahole.

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
[afa: ported from PTXdist 0c0cec2288 to OE-core]
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>