build: Remove obsolete iree flags

Remove two obsolete iree flags IREE_TARGET_BACKENDS_TO_BUILD and
IREE_HAL_DRIVERS_TO_BUILD. They were removed from IREE codebase at
https://github.com/openxla/iree/pull/7936/.

Change-Id: If505172caca03a0c5ee4c922ad4cc8548760a013

platforms/nexus/iree.mk

diff --git a/platforms/nexus/iree.mk b/platforms/nexus/iree.mk
index 05965f4..782d93b 100644
--- a/platforms/nexus/iree.mk
+++ b/platforms/nexus/iree.mk
@@ -52,8 +52,6 @@
 	    -DCMAKE_C_COMPILER=gcc -DCMAKE_CXX_COMPILER=g++ \
 	    -DCMAKE_BUILD_TYPE=RelWithDebInfo \
 	    -DCMAKE_INSTALL_PREFIX=$(IREE_COMPILER_DIR)/install \
-	    -DIREE_HAL_DRIVERS_TO_BUILD="Dylib;VMVX" \
-	    -DIREE_TARGET_BACKENDS_TO_BUILD="DYLIB-LLVM-AOT;VMVX" \
 	    -DIREE_BUILD_TESTS=OFF \
 	    $(IREE_SRC)
 

platforms/shodan/iree.mk

diff --git a/platforms/shodan/iree.mk b/platforms/shodan/iree.mk
index 137062d..cec2ac2 100644
--- a/platforms/shodan/iree.mk
+++ b/platforms/shodan/iree.mk
@@ -52,8 +52,6 @@
 	    -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ \
 	    -DCMAKE_BUILD_TYPE=RelWithDebInfo \
 	    -DCMAKE_INSTALL_PREFIX=$(IREE_COMPILER_DIR)/install \
-	    -DIREE_HAL_DRIVERS_TO_BUILD="Dylib;VMVX" \
-	    -DIREE_TARGET_BACKENDS_TO_BUILD="DYLIB-LLVM-AOT;VMVX" \
 	    -DIREE_BUILD_TESTS=OFF \
 	    $(IREE_SRC)