Docs: Update build commands

Build commands for TF-M docs are simplified.
Dependency repos are no more needed to build docs.

Update build commands in Open CI to fit with the latest TF-M codebase.
Remove redundant env params related to dependencies.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I04d4669de9d986d497d52eb95c8e0f7e8800e87a
Depends-On: I726dc17d9aa547b8faaf35564e21f25aa9c207a9
diff --git a/build-docs.sh b/build-docs.sh
index e4fb66d..ee6b01b 100755
--- a/build-docs.sh
+++ b/build-docs.sh
@@ -13,16 +13,9 @@
 
 set -ex
 
-cd mbedtls
-git apply ../trusted-firmware-m/lib/ext/mbedcrypto/*.patch
+mkdir -p ${WORKSPACE}/trusted-firmware-m/build/docs
+cd ${WORKSPACE}/trusted-firmware-m/build/docs
 
-mkdir ../trusted-firmware-m/build
-cd ../trusted-firmware-m/build
-
-cmake -S .. -B . -DTFM_PLATFORM=arm/mps2/an521 \
-                 -DTFM_TOOLCHAIN_FILE=../toolchain_GNUARM.cmake \
-                 -DMBEDCRYPTO_PATH=../../mbedtls \
-                 -DTFM_TEST_REPO_PATH=../../tf-m-tests \
-                 -DMCUBOOT_PATH=../../mcuboot
+cmake -S ${WORKSPACE}/trusted-firmware-m/docs -B .
 cmake --build ./ -- tfm_docs_refman_html
 cmake --build ./ -- tfm_docs_userguide_html