stmhal/lcd: De-assert chip select after completing SPI transmission.

The LCD interface library fails to deassert the chip select of the LCD
after an SPI transmission.  Consequently using the SPI with other
peripherals disturbs the state of the LCD.  This patch changes
lcd.lcd_out() to deassert CS after each transmission to the LCD.

stmhal/lcd.c

@@ -121,6 +121,8 @@ STATIC void lcd_out(pyb_lcd_obj_t *lcd, int instr_data, uint8_t i) {
     }
     lcd_delay();
     HAL_SPI_Transmit(lcd->spi, &i, 1, 1000);
+    lcd_delay();
+    lcd->pin_cs1->gpio->BSRRL = lcd->pin_cs1->pin_mask; // CS=1; disable
 }
 
 // write a string to the LCD at the current cursor location