drm/msm/dsi: Remove set but not used variable 'lp'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/gpu/drm/msm/dsi/dsi_host.c: In function dsi_cmd_dma_rx:
drivers/gpu/drm/msm/dsi/dsi_host.c:1302:7: warning: variable lp set but not used [-Wunused-but-set-variable]

It is not used since commit a689554b ("drm/msm:
Initial add DSI connector support")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1570690506-83287-5-git-send-email-zhengbin13@huawei.com

drivers/gpu/drm/msm/dsi/dsi_host.c

@@ -1291,14 +1291,13 @@ static int dsi_cmd_dma_tx(struct msm_dsi_host *msm_host, int len)
 static int dsi_cmd_dma_rx(struct msm_dsi_host *msm_host,
 			u8 *buf, int rx_byte, int pkt_size)
 {
-	u32 *lp, *temp, data;
+	u32 *temp, data;
 	int i, j = 0, cnt;
 	u32 read_cnt;
 	u8 reg[16];
 	int repeated_bytes = 0;
 	int buf_offset = buf - msm_host->rx_buf;
 
-	lp = (u32 *)buf;
 	temp = (u32 *)reg;
 	cnt = (rx_byte + 3) >> 2;
 	if (cnt > 4)