fix(tf-coverity): provide MBEDTLS_DIR path for rpi3 build

The MBEDTLS_DIR path is not set by default for the rpi3
build, so it is explicitly provided as a build parameter.

Change-Id: Ie95111eb12f1e291f3bc236f242557e52b539c87
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
diff --git a/script/tf-coverity/tf-cov-make b/script/tf-coverity/tf-cov-make
index c794e94..2919676 100755
--- a/script/tf-coverity/tf-cov-make
+++ b/script/tf-coverity/tf-cov-make
@@ -866,8 +866,9 @@
 clean_build PLAT=rpi5 $(common_flags) SMC_PCI_SUPPORT=1 all
 
 # Raspberry Pi Measured Boot Discrete TPM
-make PLAT=rpi3 $(common_flags) PRELOADED_BL33_BASE=0x200000 MEASURED_BOOT=1
-    DISCRETE_TPM=1 TPM_INTERFACE=FIFO_SPI MBOOT_TPM_HASH_ALG=sha256 all
+make PLAT=rpi3 $(common_flags) PRELOADED_BL33_BASE=0x200000 \
+    MEASURED_BOOT=1 DISCRETE_TPM=1 TPM_INTERFACE=FIFO_SPI \
+    MBOOT_TPM_HASH_ALG=sha256 MBEDTLS_DIR=$(pwd)/mbedtls all
 
 # A113D (AXG) platform.
 clean_build PLAT=axg $(common_flags) SPD=opteed