remove hardcode uart pins definition for nRF52 SoCs

Each boards define its own pins.

Author: nvlsianpu

targets/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF52832/sdk_patch/sdk_config.h

@@ -6,8 +6,6 @@
 #define UART_DEFAULT_CONFIG_BAUDRATE UART0_CONFIG_BAUDRATE
 #define UART_DEFAULT_CONFIG_PARITY   UART0_CONFIG_PARITY
 #define UART_DEFAULT_CONFIG_HWFC     UART0_CONFIG_HWFC
-#define CTS_PIN_NUMBER               UART0_CONFIG_PSEL_CTS
-#define RTS_PIN_NUMBER               UART0_CONFIG_PSEL_RTS
 
 #define SPIS_DEFAULT_ORC                 NRF_DRV_SPIS_DEFAULT_ORC
 #define SPIS_DEFAULT_CONFIG_IRQ_PRIORITY SPIS1_CONFIG_IRQ_PRIORITY;