[DTV00867074][[Sanity][POWER_003]Plug dongle on USB3.0 port, AC power on, system crash.]

[Description]
Fix fs no restore issue

Change-Id: I5c93e1793202e21a12f6205dd6c0330f3327abf5
CR-Id: DTV00867074
Signed-off-by: guo-jie.wang <guo-jie.wang@mediatek.com>
diff --git a/os/linux/platform.c b/os/linux/platform.c
index d58f09d..8d8e923 100644
--- a/os/linux/platform.c
+++ b/os/linux/platform.c
@@ -325,6 +325,7 @@
 
 	if (IS_ERR(fd)) {
 		DBGLOG(INIT, INFO, "[nvram_read] : failed to open!!\n");
+		set_fs(old_fs);
 		return -1;
 	}
 
@@ -389,6 +390,7 @@
 
 	if (IS_ERR(fd)) {
 		DBGLOG(INIT, INFO, "[nvram_write] : failed to open!!\n");
+		set_fs(old_fs);
 		return -1;
 	}