spi: npcm-fiu: remove set but not used variable 'retlen'

drivers/spi/spi-npcm-fiu.c: In function npcm_fiu_read:
drivers/spi/spi-npcm-fiu.c:472:9: warning:
 variable retlen set but not used [-Wunused-but-set-variable]

It is never used, so remove it.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20190905072436.23932-1-yuehaibing@huawei.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-npcm-fiu.c

@@ -469,7 +469,6 @@ static int npcm_fiu_read(struct spi_mem *mem, const struct spi_mem_op *op)
 {
 	u8 *data = op->data.buf.in;
 	int i, readlen, currlen;
-	size_t retlen = 0;
 	u8 *buf_ptr;
 	u32 addr;
 	int ret;
@@ -494,8 +493,6 @@ static int npcm_fiu_read(struct spi_mem *mem, const struct spi_mem_op *op)
 		currlen -= 16;
 	} while (currlen > 0);
 
-	retlen = i;
-
 	return 0;
 }