linux-aspeed: Add devmem kernel parameter

From the kernel commit message:

    For security reasons, some configuration needs to run without /dev/mem
    but on some occasions, to debug HW for instance, it's still useful to
    be able to reboot the system with access to physical memory.

    Add a kernel parameter which activates the /dev/mem device only when
    'mem.devmem' is enabled.

Change-Id: Id520ef87671a6b357cab86e7570364874b6ac805
Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/recipes-kernel/linux/ast2400/defconfig b/recipes-kernel/linux/ast2400/defconfig
index faacdc6..4e3bcd3 100644
--- a/recipes-kernel/linux/ast2400/defconfig
+++ b/recipes-kernel/linux/ast2400/defconfig
@@ -125,7 +125,7 @@
 # CONFIG_SERIO is not set
 # CONFIG_VT is not set
 # CONFIG_LEGACY_PTYS is not set
-# CONFIG_DEVMEM is not set
+CONFIG_DEVMEM_BOOTPARAM=y
 CONFIG_SERIAL_8250=y
 # CONFIG_SERIAL_8250_DEPRECATED_OPTIONS is not set
 CONFIG_SERIAL_8250_CONSOLE=y
diff --git a/recipes-kernel/linux/ast2500/defconfig b/recipes-kernel/linux/ast2500/defconfig
index 626d67b..5e8e9b9 100755
--- a/recipes-kernel/linux/ast2500/defconfig
+++ b/recipes-kernel/linux/ast2500/defconfig
@@ -128,7 +128,7 @@
 # CONFIG_SERIO is not set
 # CONFIG_VT is not set
 # CONFIG_LEGACY_PTYS is not set
-# CONFIG_DEVMEM is not set
+CONFIG_DEVMEM_BOOTPARAM=y
 CONFIG_SERIAL_8250=y
 # CONFIG_SERIAL_8250_DEPRECATED_OPTIONS is not set
 CONFIG_SERIAL_8250_CONSOLE=y
diff --git a/recipes-kernel/linux/linux-aspeed_git.bb b/recipes-kernel/linux/linux-aspeed_git.bb
index 0a29f95..5dbd607 100644
--- a/recipes-kernel/linux/linux-aspeed_git.bb
+++ b/recipes-kernel/linux/linux-aspeed_git.bb
@@ -1,6 +1,6 @@
 KBRANCH ?= "dev-4.18"
 LINUX_VERSION ?= "4.18.16"
 
-SRCREV="ac3d5d4192df9eeeb513cc2a6259718335a4f569"
+SRCREV="d5a1e731ff9ad09c61756fe0e0ebfbb65ad3405b"
 
 require linux-aspeed.inc