drivers: Add support for X-Powers AXP209 PMU

Change-Id: I1de0e656a38527b172af1d0b5bcd97acbfc03bf0
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/4591
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
diff --git a/src/drivers/Makefile.inc b/src/drivers/Makefile.inc
index 7b1e4ca..34ae62e 100644
--- a/src/drivers/Makefile.inc
+++ b/src/drivers/Makefile.inc
@@ -34,4 +34,5 @@
 subdirs-y += ti
 subdirs-y += ipmi
 subdirs-y += elog
+subdirs-y += xpowers
 subdirs-$(CONFIG_ARCH_X86) += pc80