hwc2: Ignore Notify to non-existance file node

Secure display will try to signal both wled and labibb. However
the display function did not use WLED to drive backlight, nor use
LAB/IBB of the PMIC to provide the LCD bias on B4S4.
So just bypass the file node writing if it's invalid.

Bug: 111504659
Test: Manually tested with keystore_cli_v2

Change-Id: Ia7ea7c13a7635a7f81ae6d76dd1627791c7e49bf
diff --git a/sdm/libs/hwc2/hwc_display_primary.cpp b/sdm/libs/hwc2/hwc_display_primary.cpp
index b1eeecd..6eaf11d 100644
--- a/sdm/libs/hwc2/hwc_display_primary.cpp
+++ b/sdm/libs/hwc2/hwc_display_primary.cpp
@@ -73,6 +73,10 @@
 
 DisplayError HWCDisplayPrimary::PMICInterface::Notify(bool secure_display_start) {
   std::string str_sd_start = secure_display_start ? std::to_string(1) : std::to_string(0);
+  if (fd_lcd_bias_ < 0 || fd_wled_ < 0) {
+    DLOGI("Ignore notify because fd_lcd_bias_ or fd_wled_ open failed");
+    return kErrorNotSupported;
+  }
   ssize_t err = ::pwrite(fd_lcd_bias_, str_sd_start.c_str(), str_sd_start.length(), 0);
   if (err <= 0) {
     DLOGE("Write failed for lcd_bias, Error = %s", strerror(errno));