Allow overriding OCC_P10_SITE

- Updated occ-p10 makefile to allow overriding OCC_P10_SITE from the environment
- Removed OCC_P10_SITE_METHOD since buildroot can detect the right method

Signed-off-by: Nick Bofferding bofferdn@us.ibm.com
diff --git a/openpower/package/occ-p10/occ-p10.mk b/openpower/package/occ-p10/occ-p10.mk
index be927fd..a4c8697 100644
--- a/openpower/package/occ-p10/occ-p10.mk
+++ b/openpower/package/occ-p10/occ-p10.mk
@@ -8,8 +8,7 @@
 # TODO: WORKAROUND: Need to reenable next line and comment out the two lines
 # after that, when code is propagated to a public repo
 #OCC_P10_SITE ?= $(call github,open-power,occ,$(OCC_P10_VERSION))
-OCC_P10_SITE = git@github.ibm.com:open-power/occ.git
-OCC_P10_SITE_METHOD=git
+OCC_P10_SITE ?= git@github.ibm.com:open-power/occ.git
 
 OCC_P10_LICENSE = Apache-2.0