recipe: anchor regexps in COMPATIBLE_MACHINE

* bitbake is using re.match, so raspberrypi actually matches with anything
  ^raspberrypi.* which currently works, but it will also match with hypothetical
  raspberrypi-is-no-more-this-is-banana-now MACHINE which isn't intended by
  this COMPATIBLE_MACHINE.

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

recipes-devtools/python/rpi-gpio_0.6.2.bb

@@ -17,5 +17,5 @@ S = "${WORKDIR}/${SRCNAME}-${PV}"
 
 inherit distutils
 
-COMPATIBLE_MACHINE = "raspberrypi"
+COMPATIBLE_MACHINE = "^rpi$"
 

recipes-devtools/python/rpio_0.10.0.bb

@@ -14,7 +14,7 @@ S = "${WORKDIR}/${SRCNAME}-${PV}"
 
 inherit setuptools
 
-COMPATIBLE_MACHINE = "raspberrypi"
+COMPATIBLE_MACHINE = "^rpi$"
 
 RDEPENDS_${PN} = "\
     python-logging \