staging/fbtft: Hush checkpatch.pl warning about unnecessary line continuations

Use a single string literal as the fmt argument passed to dev_err()
instead of multiple string literals split with an embedded backslash
character.
Signed-off-by: Alexander Kapshuk <alexander.kapshuk@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fbtft/fb_ssd1331.c

@@ -130,16 +130,16 @@ static int set_gamma(struct fbtft_par *par, u32 *curves)
 	for (i = 0; i < 63; i++) {
 		if (i > 0 && curves[i] < 2) {
 			dev_err(par->info->device,
-				"Illegal value in Grayscale Lookup Table at index %d. " \
-				"Must be greater than 1\n", i);
+				"Illegal value in Grayscale Lookup Table at index %d. Must be greater than 1\n",
+				i);
 			return -EINVAL;
 		}
 		acc += curves[i];
 		tmp[i] = acc;
 		if (acc > 180) {
 			dev_err(par->info->device,
-				"Illegal value(s) in Grayscale Lookup Table. " \
-				"At index=%d, the accumulated value has exceeded 180\n", i);
+				"Illegal value(s) in Grayscale Lookup Table. At index=%d, the accumulated value has exceeded 180\n",
+				i);
 			return -EINVAL;
 		}
 	}