package/rpi-userland: install all of our .pc files the same way

Install bcm_host the same way we install egl.pc and glesv2.pc, using
the cmake lists.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>