spi/bcm63xx: Remove the unused function bcm_spi_readw()

The function bcm_spi_readw is defined in the spi-bcm63xx.c file, but
not called elsewhere, so remove this unused function.

drivers/spi/spi-bcm63xx.c:160:19: warning: unused function 'bcm_spi_readw'.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=4242
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230228023243.118429-1-jiapeng.chong@linux.alibaba.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-bcm63xx.c

@@ -157,16 +157,6 @@ static inline u8 bcm_spi_readb(struct bcm63xx_spi *bs,
 	return readb(bs->regs + bs->reg_offsets[offset]);
 }
 
-static inline u16 bcm_spi_readw(struct bcm63xx_spi *bs,
-				unsigned int offset)
-{
-#ifdef CONFIG_CPU_BIG_ENDIAN
-	return ioread16be(bs->regs + bs->reg_offsets[offset]);
-#else
-	return readw(bs->regs + bs->reg_offsets[offset]);
-#endif
-}
-
 static inline void bcm_spi_writeb(struct bcm63xx_spi *bs,
 				  u8 value, unsigned int offset)
 {