[bsp][drivers][soft_spi] unify the software SPI driver

Author: CYFS3

bsp/nxp/lpc/lpc55sxx/libraries/drivers/SConscript

@@ -43,9 +43,6 @@ if  GetDepend('BSP_USING_I2S'):
 if  GetDepend('BSP_USING_WM8904'):
     src += ['drv_sound_wm8904.c']
 
-if GetDepend('BSP_USING_SOFT_SPI'):
-    src += ['drv_soft_spi.c']
-
 if GetDepend('BSP_USING_LCD'):
     src += ['drv_st7796.c']
     src += ['sample/lcd_sample.c']