configs/clicker2-stm32: Fixes minor SPI configuration issues

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Conflicts:
	configs/nucleo-l476rg/src/stm32_spi.c (resolved)

realloc(): When realloc() has to fall back to calling malloc(), size including overhead was being provided to malloc(), causing a slightly larger allocation than needed.  Noted by initialkjc@yahoo.com