Make constexpr constants in headers inline constexpr (#29279)

* Make constexpr constants in headers inline constexpr

This makes the linker deduplicate these constants, instead of emitting one
definition per compilation unit. E.g. chip::System::Clock::kZero currently
exists >10 times in the chip-tool binary.

* Restyle
diff --git a/src/platform/nrfconnect/wifi/NrfWiFiDriver.h b/src/platform/nrfconnect/wifi/NrfWiFiDriver.h
index 7b57607..d1fc765 100644
--- a/src/platform/nrfconnect/wifi/NrfWiFiDriver.h
+++ b/src/platform/nrfconnect/wifi/NrfWiFiDriver.h
@@ -25,9 +25,9 @@
 namespace DeviceLayer {
 namespace NetworkCommissioning {
 
-constexpr uint8_t kMaxWiFiNetworks                  = 1;
-constexpr uint8_t kWiFiScanNetworksTimeOutSeconds   = 10;
-constexpr uint8_t kWiFiConnectNetworkTimeoutSeconds = 35;
+inline constexpr uint8_t kMaxWiFiNetworks                  = 1;
+inline constexpr uint8_t kWiFiScanNetworksTimeOutSeconds   = 10;
+inline constexpr uint8_t kWiFiConnectNetworkTimeoutSeconds = 35;
 
 class NrfWiFiScanResponseIterator : public Iterator<WiFiScanResponse>
 {