baseboard/kukui: reduce UART_TX buffer size to 4096
kodama's build failure due to out of space.
Reduce the TX buffer size.
Note: This change should not cherry-pick to firmware branch.
TEST=make buildall
BRANCH=none
/* Increase tx buffer size, as we'd like to stream EC log to AP. */
#undef CONFIG_UART_TX_BUF_SIZE
-#define CONFIG_UART_TX_BUF_SIZE 8192
+#define CONFIG_UART_TX_BUF_SIZE 4096
/* To be able to indicate the device is in tablet mode. */
#define CONFIG_TABLET_MODE
