hw-mgmt: scripts: Fix init error fox SimX paltform

Fix SKU/platform reading if it's not exists. This can be when running on
SimX platform.

log messages example before fix:

/usr/bin/hw-management.sh: line 61: /sys/devices/virtual/dmi/id/board_name: No such file or directory
/usr/bin/hw-management.sh: line 62: /sys/devices/virtual/dmi/id/product_sku: No such file or directory
/usr/bin/hw-management-helpers.sh: line 325: /var/run/hw-management/events/: Is a directory

Signed-off-by: Oleksandr Shamray <oleksandrs@nvidia.com>

usr/usr/bin/hw-management-ready.sh

@@ -40,8 +40,8 @@
 #              Report start of hw-management service to console and logger.
 
 source hw-management-helpers.sh
-board_type=`cat /sys/devices/virtual/dmi/id/board_name`
-product_sku=`cat /sys/devices/virtual/dmi/id/product_sku`
+[ -f "$board_type_file" ] && board_type=$(< $board_type_file) || board_type="Unknown"
+[ -f "$sku_file" ] && product_sku=$(< $sku_file) || product_sku="Unknown"
 
 if systemctl is-active --quiet hw-management; then
         echo "Error: HW management service is already active."

usr/usr/bin/hw-management.sh

@@ -58,8 +58,8 @@
 #
 
 source hw-management-helpers.sh
-board_type=$(< $board_type_file)
-sku=$(< $sku_file)
+[ -f "$board_type_file" ] && board_type=$(< $board_type_file) || board_type="Unknown"
+[ -f "$sku_file" ] && sku=$(< $sku_file) || sku="Unknown"
 source hw-management-devtree.sh
 # Local constants and variables