package/meson: fix CPU familly

package/meson: fix CPU familly

As explained in [0], meson recognises a certain set of CPU famillies,
whose names slightly differ from those we know them as.

If we don't pass the proper cpu_familly, meson whines:
    WARNING: Unknown CPU family 'i686', please report this at [...]

Subsequently, packages that use that to decide on what they should build
and how they should build it, fail to build. That is the case for the
upcoming systemd-boot, for example.

Fix that by using the list propvided by the meson documentation [0].

[0] https://mesonbuild.com/Reference-tables.html#cpu-families

Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
[yann.morin.1998@free.fr:
  - split in its own patch
  - imnprove commit log
]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>