package/bcm2835: bump version to 1.71

- bump version to 1.71
- change home page and download URL to https

Changelog (since 1.71):

 - 1.71, Added SMI bus support, courtesy of Benoit Bouchez, including new
   functions: bcm2835_smi_begin(), bcm2835_smi_end(), bcm2835_smi_set_timing(),
   bcm2835_smi_write(), bcm2835_smi_read().

Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>