Remove unwanted #ifdef form nRF5 targets spi_api implementations.

Reduce size of no-init section to precisely fit to size of vector in RAM.

Author: nvlsianpu

targets/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF52832/device/TOOLCHAIN_ARM_STD/nRF52832.sct

@@ -18,10 +18,10 @@ LR_IROM1 0x1C000 0x0064000  {
    *(InRoot$$Sections)
    .ANY (+RO)
   }
-  RW_IRAM0 0x20002EF8 UNINIT 0x00000100  { ;no init section
+  RW_IRAM0 0x20002EF8 UNINIT 0x000000D8  { ;no init section
         *(noinit)
   }
-  RW_IRAM1 0x20002FF8 0x0000D008  {
+  RW_IRAM1 0x20002FD0 0x0000D030  {
    .ANY (+RW +ZI)
   }
 }

targets/TARGET_NORDIC/TARGET_NRF5/spi_api.c

@@ -258,9 +258,7 @@ void spi_init(spi_t *obj,
         spi_info_t *p_spi_info = &m_spi_info[i];
         if (!p_spi_info->initialized) {
 
-#ifndef HARDWIRE_SPI_TWI_INTERRUPT         
             NVIC_SetVector(spi_hanlder_desc[i].IRQn, spi_hanlder_desc[i].vector);
-#endif
 
             p_spi_info->sck_pin   = (uint8_t)sclk;
             p_spi_info->mosi_pin  = (mosi != NC) ?