librtpi: direct SRC_URI to pull from gcrisan's repo
librtpi: direct SRC_URI to pull from gcrisan's repo

Use github.com/gratian's librtpi repo as the recipe upstream, since it
is the most forward source and is externally accessible.

Signed-off-by: Alex Stewart <04cdb2793e4fb0120cc30d1c823099f3862701f4@ni.com>
Acked-by: Gratian Crisan <17cf39b7426cfdea7dd491f7105a23841aaa302f@ni.com>

ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt