samples: Fix absolute path in target_sources()

Use
target_sources(app PRIVATE ${ZEPHYR_BASE}/[path to sources])
instead of
target_sources(app PRIVATE $ENV{ZEPHYR_BASE}/[path to sources])

Signed-off-by: Sebastian Głąb <sebastian.glab@nordicsemi.no>

Author: nordic-segl

samples/drivers/audio/dmic/CMakeLists.txt

@@ -8,4 +8,4 @@ cmake_minimum_required(VERSION 3.20.0)
 find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
 project(dmic)
 
-target_sources(app PRIVATE $ENV{ZEPHYR_BASE}/samples/drivers/audio/dmic/src/main.c)
+target_sources(app PRIVATE ${ZEPHYR_BASE}/samples/drivers/audio/dmic/src/main.c)

samples/sensor/qdec/CMakeLists.txt

@@ -8,4 +8,4 @@ cmake_minimum_required(VERSION 3.20.0)
 find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
 project(qdec_sensor)
 
-target_sources(app PRIVATE $ENV{ZEPHYR_BASE}/samples/sensor/qdec/src/main.c)
+target_sources(app PRIVATE ${ZEPHYR_BASE}/samples/sensor/qdec/src/main.c)

samples/subsys/settings/CMakeLists.txt

@@ -8,4 +8,4 @@ cmake_minimum_required(VERSION 3.20.0)
 find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
 project(settings_sample)
 
-target_sources(app PRIVATE $ENV{ZEPHYR_BASE}/samples/subsys/settings/src/main.c)
+target_sources(app PRIVATE ${ZEPHYR_BASE}/samples/subsys/settings/src/main.c)

tests/benchmarks/current_consumption/system_off/CMakeLists.txt

@@ -9,7 +9,7 @@ set(KCONFIG_ROOT $ENV{ZEPHYR_BASE}/samples/boards/nordic/system_off/Kconfig)
 find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
 project(system_off)
 
-target_sources(app PRIVATE $ENV{ZEPHYR_BASE}/samples/boards/nordic/system_off/src/main.c)
+target_sources(app PRIVATE ${ZEPHYR_BASE}/samples/boards/nordic/system_off/src/main.c)
 if(CONFIG_APP_USE_NRF_RETENTION OR CONFIG_APP_USE_RETAINED_MEM)
-  target_sources(app PRIVATE $ENV{ZEPHYR_BASE}/samples/boards/nordic/system_off/src/retained.c)
+  target_sources(app PRIVATE ${ZEPHYR_BASE}/samples/boards/nordic/system_off/src/retained.c)
 endif()