at32ap700x spi: enable pullups on MISO

This is a minor tweak to the at32ap700x pin configuration for the SPI
input pin (MISO), enabling the on-chip weak pullup (typical 190K) to

  (a) ensure a fixed data value for missing or input-only slaves;

  (b) prevent power waste associated with inputs floating near VDDIO/2.

Atmel's boards have no external pullup or pulldown on these pins, so
it's unlikely other boards would address these issues with external
pulldowns.  Were there trouble, board-specific code could turn off
the relevant pullup(s).
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NHaavard Skinnemoen <haavard.skinnemoen@atmel.com>

arch/avr32/mach-at32ap/at32ap700x.c

@@ -1181,7 +1181,8 @@ at32_add_device_spi(unsigned int id, struct spi_board_info *b, unsigned int n)
 	switch (id) {
 	case 0:
 		pdev = &atmel_spi0_device;
-		select_peripheral(PA(0),  PERIPH_A, 0);	/* MISO	 */
+		/* pullup MISO so a level is always defined */
+		select_peripheral(PA(0),  PERIPH_A, AT32_GPIOF_PULLUP);
 		select_peripheral(PA(1),  PERIPH_A, 0);	/* MOSI	 */
 		select_peripheral(PA(2),  PERIPH_A, 0);	/* SCK	 */
 		at32_spi_setup_slaves(0, b, n, spi0_pins);
@@ -1189,7 +1190,8 @@ at32_add_device_spi(unsigned int id, struct spi_board_info *b, unsigned int n)
 
 	case 1:
 		pdev = &atmel_spi1_device;
-		select_peripheral(PB(0),  PERIPH_B, 0);	/* MISO  */
+		/* pullup MISO so a level is always defined */
+		select_peripheral(PB(0),  PERIPH_B, AT32_GPIOF_PULLUP);
 		select_peripheral(PB(1),  PERIPH_B, 0);	/* MOSI  */
 		select_peripheral(PB(5),  PERIPH_B, 0);	/* SCK   */
 		at32_spi_setup_slaves(1, b, n, spi1_pins);