Move default multihal configuration file to /vendor/...

Move default multihal configuration file path to
/vendor/etc/sensors/hals.conf. Retained old definition but changed
varible name to mark it deprecated. get_so_paths() is modified
to search both new and old path for configuration file.

MULTI_HAL_CONFIG_FILE_PATH is only used by hidl default
implementation at this moment outside multihal module.

Bug: 35947802
Test: build ok, sensor works on 2017 devices
Change-Id: I443ff71fa194383646108c8eb0c5438d150a5886
diff --git a/modules/sensors/multihal.h b/modules/sensors/multihal.h
index 210c7cc..234f2f0 100644
--- a/modules/sensors/multihal.h
+++ b/modules/sensors/multihal.h
@@ -19,7 +19,10 @@
 #include <hardware/sensors.h>
 #include <hardware/hardware.h>
 
-static const char* MULTI_HAL_CONFIG_FILE_PATH = "/system/etc/sensors/hals.conf";
+static const char* MULTI_HAL_CONFIG_FILE_PATH = "/vendor/etc/sensors/hals.conf";
+
+// Depracated because system partition HAL config file does not satisfy treble requirements.
+static const char* DEPRECATED_MULTI_HAL_CONFIG_FILE_PATH = "/system/etc/sensors/hals.conf";
 
 struct sensors_module_t *get_multi_hal_module_info(void);