grandteton: Fix error in detecting HGX Presence

Summary:
We were handling the wrong exception. kv::get() throws
std::filesystem::filesystem_error and not kv::key_does_not_exist.

Test Plan:
Copy libhgx package onto system and ensure
we can run fw-util hgx --version.

Reviewed By: williamspatrick

Differential Revision: D52485981

fbshipit-source-id: 133fdb939ff410a01fc4d23d5430fb7d85f6bd1b

meta-facebook/meta-grandteton/recipes-grandteton/hgx/files/hgx.cpp

@@ -157,7 +157,7 @@ GPUConfig getConfig() {
     } else {
       return GPU_CONFIG_UNKNOWN;
     }
-  } catch (kv::key_does_not_exist& e) {
+  } catch (std::filesystem::filesystem_error& e) {
     const int hgx_eeprom_bus = 0x9;
     int fd = 0;
     uint8_t tlen, rlen;