mk: Generalize kernel loadaddr

Introduce ADK_TARGET_KERNEL_LOADADDR symbol holding the right kernel
loadaddr depending on chosen target system instead of hard-coding the
value into kernel-vars.mk.

Signed-off-by: Phil Sutter <phil@nwl.cc>

mk/kernel-vars.mk

@@ -29,8 +29,8 @@ else
 KERNEL_MAKE_OPTS+=	HOSTCFLAGS='${HOST_CFLAGS}'
 endif
 
-ifeq ($(ADK_TARGET_SYSTEM_BANANA_PRO)$(ADK_TARGET_SYSTEM_ORANGE_PI0),y)
+ifneq ($(ADK_TARGET_KERNEL_LOADADDR),)
-KERNEL_MAKE_OPTS+=	LOADADDR=0x40008000
+KERNEL_MAKE_OPTS+=	LOADADDR=$(ADK_TARGET_KERNEL_LOADADDR)
 endif
 
 KERNEL_MAKE_ENV:=	PATH="${TOOLCHAIN_DIR}/usr/bin:${STAGING_HOST_DIR}/usr/bin:$$PATH"

target/config/Config.in.kernelfmt

@@ -63,3 +63,8 @@ config ADK_TARGET_KERNEL
 
 config ADK_TARGET_KERNEL_WITH_COMPRESSION
 	bool
+
+config ADK_TARGET_KERNEL_LOADADDR
+	hex
+	default 0x40008000 if ADK_TARGET_SYSTEM_BANANA_PRO
+	default 0x40008000 if ADK_TARGET_SYSTEM_ORANGE_PI0