fwcfg: update command to make it more accurate and general

Currently, this command can not get available disk in bootc host,
besides that, this command also not setup the output's units, it
will get a wrong number if the command execute in a large system(
disk size > 1T).So update the command to fix above errors

Signed-off-by: Leidong Wang <[email protected]>

Author: leidwang

qemu/tests/cfg/fwcfg.cfg

@@ -6,7 +6,7 @@
     vmcoreinfo = yes
     start_vm = no
     tmp_dir = "/var/tmp"
-    get_avail_disk = df -h /home | grep home | awk -F "G" '{print $3}'
+    get_avail_disk = df -BG /home | awk 'NR==2 {print $4}' | sed 's/G//'
     unzip_cmd = 'powershell -command "Expand-Archive %s:\Memory.dmp.zip %s:"'
     unzip_timeout = 1800
     dump_file = Memory.dmp

qemu/tests/cfg/fwcfg_enable.cfg

@@ -9,7 +9,7 @@
     start_vm = no
     setup_verifier = no
     tmp_dir = "/home/tmp"
-    get_avail_disk = df -h /home | grep home | awk -F "G" '{print $3}'
+    get_avail_disk = df -BG /home | awk 'NR==2 {print $4}' | sed 's/G//'
     unzip_cmd = 'powershell -command "Expand-Archive %s:\Memory.dmp.zip %s:"'
     unzip_timeout = 1800
     dump_file = Memory.dmp

qemu/tests/cfg/win_virtio_driver_update_test.cfg

@@ -288,7 +288,7 @@
             device_name = "QEMU FwCfg Device"
             device_hwid = '"ACPI\VEN_QEMU&DEV_0002"'
             tmp_dir = "/home/tmp"
-            get_avail_disk = df -h /home | grep home | awk -F "G" '{print $3}'
+            get_avail_disk = df -BG /home | awk 'NR==2 {print $4}' | sed 's/G//'
             unzip_cmd = 'powershell -command "Expand-Archive %s:\Memory.dmp.zip %s:"'
             unzip_timeout = 1800
             dump_file = Memory.dmp