UBLOX_ODIN_EVK_W2 - add BUTTON1/2 definitions

UBLOX_ODIN_EVK_W2 is missing the abstract button definitions originally
introduced with PR https://github.com/ARMmbed/mbed-os/pull/4249.

Fix two tab to spaces issues on the go as well.

targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F439xI/TARGET_UBLOX_EVK_ODIN_W2/PinNames.h

@@ -156,6 +156,11 @@ typedef enum {
     LED4    = D10,
     SW0     = PF_2,   // Switch-0
     SW1     = PB_6,   // Green / Switch-1
+
+    // Standardized button names
+    BUTTON1 = SW0,
+    BUTTON2 = SW1,
+
     // ST-Link
     USBRX   = PA_10,
     USBTX   = PA_9,