staging: fbtft: Fix mutex and spinlock without comment warning

Adhere to Linux kernel coding style

Reported by checkpatch:

CHECK: spinlock_t definition without comment
CHECK: mutex definition without comment
Signed-off-by: Riyan Dhiman <riyandhiman14@gmail.com>
Link: https://lore.kernel.org/r/20240727093106.11214-1-riyandhiman14@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fbtft/fbtft.h

@@ -202,6 +202,7 @@ struct fbtft_par {
 	u8 *buf;
 	u8 startbyte;
 	struct fbtft_ops fbtftops;
+	/* Spinlock to ensure thread-safe access to dirty_lines_start and dirty_lines_end */
 	spinlock_t dirty_lock;
 	unsigned int dirty_lines_start;
 	unsigned int dirty_lines_end;
@@ -218,6 +219,7 @@ struct fbtft_par {
 	} gpio;
 	const s16 *init_sequence;
 	struct {
+		/* Mutex to synchronize access to gamma curve locking */
 		struct mutex lock;
 		u32 *curves;
 		int num_values;