drivers: framework for a generic flash driver

The framework for a generic flash driver.

Change-Id: I030eb6d88338f4d6611fc6e5cae42ac586cfdb12
Signed-off-by: Baohong Liu <baohong.liu@intel.com>
diff --git a/drivers/Kconfig b/drivers/Kconfig
index 179af16..0fae61a 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -67,4 +67,6 @@
 
 source "drivers/nble/Kconfig"
 
+source "drivers/flash/Kconfig"
+
 endmenu