installer: Fix root_dev() for correct INVENTORY mounting

root_dev() function in the installer script checks for the root device in
/dev/root, considering that this file will be always a symbolic link, which
is not true for some platforms, such as in some NVIDIA devices, where
/dev/root it's just a regular file block device. For these cases, INVENTORY
partition will not be found and /persist/installer will be used instead.
This commit fixes this issue by checking if /dev/root is a symbolic link or
a file block device.

Signed-off-by: Renê de Souza Pinto <rene@renesp.com.br>

Author: rene

pkg/installer/install

@@ -99,7 +99,7 @@ root_dev() {
    local MAJOR
    local MINOR
    local DEV
-   if [ -L /dev/root ] ; then
+   if [ -L /dev/root ] || [ -b /dev/root ] ; then
       DEV=$(readlink -f /dev/root)
       MAJOR=$(( 0x$(stat -c '%t' "$DEV") + 0 ))
       MINOR=$(( 0x$(stat -c '%T' "$DEV") + 0 ))