Fix /proc/bootconfig to select double or single quotes
corrctly according to the value.

If a bootconfig value includes a double quote character,
we must use single-quotes to quote that value.

This modifies if() condition and blocks for avoiding
double-quote in value check in 2 places. Anyway, since
xbc_array_for_each_value() can handle the array which
has a single node correctly.
Thus,

if (vnode && xbc_node_is_array(vnode)) {
	xbc_array_for_each_value(vnode)	/* vnode->next != NULL */
		...
} else {
	snprintf(val); /* val is an empty string if !vnode */
}

is equivalent to

if (vnode) {
	xbc_array_for_each_value(vnode)	/* vnode->next can be NULL */
		...
} else {
	snprintf("");	/* value is always empty */
}

Link: http://lkml.kernel.org/r/159230244786.65555.3763894451251622488.stgit@devnote2

Cc: stable@vger.kernel.org
Fixes: c1a3c36017d4 ("proc: bootconfig: Add /proc/bootconfig to show boot config list")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

Add /proc/bootconfig which shows the list of key-value pairs
in boot config. Since after boot, all boot configs and tree
are removed, this interface just keep a copy of key-value
pairs in text.

Link: http://lkml.kernel.org/r/157867225967.17873.12155805787236073787.stgit@devnote2

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>