labs/yocto-sdk: add populate_sdk fix for stm32mp1

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>

labs/yocto-sdk/yocto-sdk.tex

@@ -15,10 +15,18 @@ \section{Build the SDK}
 other one allowing for application development. We will use the latter one
 here.
 
-First, build an SDK for the \code{bootlinlabs-image-minimal} image, with
+\if\defstring{\labboard}{stm32mp1}
+On \code{stm32mp1}, we first need to remove ST host tooling that we
+don't need and that currently fails to build anyway.
+
+So, remove all the lines touching \code{TOOLCHAIN_HOST_TASK} in
+\code{meta-st-stm32mp/conf/machine/include/st-machine-common-stm32mp.inc}.
+\fi
+
+Build an SDK for the \code{bootlinlabs-image-minimal} image, with
 the \code{populate_sdk} task.
 
-Once the SDK is generated, a script will be available at
+Once the SDK is generated, a script will be available in
 \code{tmp/deploy/sdk}.
 
 \section{Install the SDK}