staging: wilc1000: spi: Use new structure for SPI transfer delays

In a recent change to the SPI subsystem in commit <bebcfd27>
("spi: introduce `delay` field for `spi_transfer` +
spi_transfer_delay_exec()"), a new `delay` struct was added
to replace the `delay_usecs`. This change replaces the current
`delay_usecs` with `delay` for this driver.

The `spi_transfer_delay_exec()` function [in the SPI framework] makes sure
that both `delay_usecs` & `delay` are used (in this order to preserve
backwards compatibility).
Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
Link: https://lore.kernel.org/r/20200304074319.22107-1-sergiu.cuciurean@analog.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wilc1000/spi.c

@@ -228,7 +228,10 @@ static int wilc_spi_tx(struct wilc *wilc, u8 *b, u32 len)
 		struct spi_transfer tr = {
 			.tx_buf = b,
 			.len = len,
-			.delay_usecs = 0,
+			.delay = {
+				.value = 0,
+				.unit = SPI_DELAY_UNIT_USECS
+			},
 		};
 		char *r_buffer = kzalloc(len, GFP_KERNEL);
 
@@ -269,7 +272,10 @@ static int wilc_spi_rx(struct wilc *wilc, u8 *rb, u32 rlen)
 		struct spi_transfer tr = {
 			.rx_buf = rb,
 			.len = rlen,
-			.delay_usecs = 0,
+			.delay = {
+				.value = 0,
+				.unit = SPI_DELAY_UNIT_USECS
+			},
 
 		};
 		char *t_buffer = kzalloc(rlen, GFP_KERNEL);
@@ -311,7 +317,10 @@ static int wilc_spi_tx_rx(struct wilc *wilc, u8 *wb, u8 *rb, u32 rlen)
 			.tx_buf = wb,
 			.len = rlen,
 			.bits_per_word = 8,
-			.delay_usecs = 0,
+			.delay = {
+				.value = 0,
+				.unit = SPI_DELAY_UNIT_USECS
+			},
 
 		};