arm-bsp/tf-m/fpv-rd-kronos: Use apply_local_src_patches bbclass

Instead using a custom do_patch postfunc to apply patches from tf-m repo,
make usage of the apply_local_src_patches bbclass which keeps track if
the patches were already applied avoiding errors when the do_patch reruns
in an already processed build.

Signed-off-by: Diego Sueiro <diego.sueiro@arm.com>