arch/stm32h7: Fix nxstyle errors

arch/arm/src/stm32h7/stm32_bbsram.h:

    * Fix nxstyle issues.

arch/arm/src/stm32h7/stm32_bbsram.h

@@ -86,7 +86,7 @@ struct bbsramd_s
 {
   uint8_t flags;               /* The crc is valid and the file was closed */
   uint8_t fileno;              /* The minor number */
-  uint16_t len;                /* Total Bytes in this file*/
+  uint16_t len;                /* Total Bytes in this file */
   struct timespec lastwrite;   /* Last write time */
 };
 
@@ -147,7 +147,7 @@ int stm32_bbsraminitialize(char *devpath, int *sizes);
 *
 * Assumptions:
 *
-****************************************************************************/
+*****************************************************************************/
 
 #if defined(CONFIG_STM32H7_SAVE_CRASHDUMP)
 int stm32_bbsram_savepanic(int fileno, uint8_t *context, int length);