mach-snapdragon: move default environment to a file

Make use of CONFIG_DEFAULT_ENV_FILE and move the default qcom
environment to a file under board/qualcomm.

This is much cleaner and means we don't need to recompile on changing
the environment.

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>
diff --git a/configs/qcom_defconfig b/configs/qcom_defconfig
index 22ce7db..4942237 100644
--- a/configs/qcom_defconfig
+++ b/configs/qcom_defconfig
@@ -36,6 +36,8 @@
 CONFIG_CMD_LOG=y
 CONFIG_OF_LIVE=y
 CONFIG_BUTTON_QCOM_PMIC=y
+CONFIG_USE_DEFAULT_ENV_FILE=y
+CONFIG_DEFAULT_ENV_FILE="board/qualcomm/default.env"
 CONFIG_CLK=y
 CONFIG_CLK_QCOM_APQ8016=y
 CONFIG_CLK_QCOM_APQ8096=y