bsp: cvitek: SConstruct: optimize drivers_path_prefix

For bsp/cvitek, all drivers related files are moved to the directory
bsp/cvitek/drivers, so the drivers_path_prefix processing in the
SConstruct of the three bsp projects can be simplified.

Signed-off-by: Chen Wang <unicorn_wang@outlook.com>

bsp/cvitek/c906_little/SConstruct

@@ -26,10 +26,7 @@ Export('rtconfig')
 
 SDK_ROOT = os.path.abspath('./')
 
-if os.path.exists(SDK_ROOT + '/drivers'):
-    drivers_path_prefix = SDK_ROOT + '/drivers'
-else:
-    drivers_path_prefix = os.path.dirname(SDK_ROOT) + '/drivers'
+drivers_path_prefix = os.path.dirname(SDK_ROOT) + '/drivers'
 
 # prepare building environment
 objs = PrepareBuilding(env, RTT_ROOT, has_libcpu = False)

bsp/cvitek/cv18xx_aarch64/SConstruct

@@ -38,10 +38,7 @@ Export('rtconfig')
 
 SDK_ROOT = os.path.abspath('./')
 
-if os.path.exists(SDK_ROOT + '/drivers'):
-    drivers_path_prefix = SDK_ROOT + '/drivers'
-else:
-    drivers_path_prefix = os.path.dirname(SDK_ROOT) + '/drivers'
+drivers_path_prefix = os.path.dirname(SDK_ROOT) + '/drivers'
 
 # prepare building environment
 objs = PrepareBuilding(env, RTT_ROOT)

bsp/cvitek/cv18xx_risc-v/SConstruct

@@ -26,10 +26,7 @@ rtconfig.ARCH='risc-v'
 
 SDK_ROOT = os.path.abspath('./')
 
-if os.path.exists(SDK_ROOT + '/drivers'):
-    drivers_path_prefix = SDK_ROOT + '/drivers'
-else:
-    drivers_path_prefix = os.path.dirname(SDK_ROOT) + '/drivers'
+drivers_path_prefix = os.path.dirname(SDK_ROOT) + '/drivers'
 
 # prepare building environment
 objs = PrepareBuilding(env, RTT_ROOT, has_libcpu = False)