kernel.bbclass: Create modules directory even if there is no modules installed

During kernel_do_install it needs to make symbol link at
${D}/lib/modules/${KERNEL_VERSION}/build, but there will not be
${D}/lib/modules/${KERNEL_VERSION} if there is no modules installed for current
image, which will result in a build failure.
Add "mkdir -p ${D}/lib/modules/${KERNEL_VERSION}" here to avoid this failure
and the need of similar changes in other scripts that also expect it to exist.

(From OE-Core rev: f2f72f8ff623d24fffbb1b0ad40bc08f05ff31dd)

Signed-off-by: He Zhe <zhe.he@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/kernel.bbclass

@@ -213,6 +213,7 @@ kernel_do_install() {
 	#
 	kerneldir=${D}${KERNEL_SRC_PATH}
 	install -d $kerneldir
+	mkdir -p ${D}/lib/modules/${KERNEL_VERSION}
 	ln -sf ${KERNEL_SRC_PATH} "${D}/lib/modules/${KERNEL_VERSION}/build"
 
 	#