esp_flash: fix the data type of delay_us

unsigned can be 16-bit on some architecture, which doesn't meet the
requirements of delaying for several hundreds of us.

components/spi_flash/include/esp_flash.h

@@ -57,7 +57,7 @@ typedef struct {
     esp_err_t (*region_protected)(void* arg, size_t start_addr, size_t size);
 
     /** Delay for at least 'us' microseconds. Called in between 'start' and 'end'. */
-    esp_err_t (*delay_us)(void *arg, unsigned us);
+    esp_err_t (*delay_us)(void *arg, uint32_t us);
 
     /** Called for get temp buffer when buffer from application cannot be directly read into/write from. */
     void *(*get_temp_buffer)(void* arg, size_t reqest_size, size_t* out_size);

components/spi_flash/include/spi_flash_chip_driver.h

@@ -152,7 +152,7 @@ struct spi_flash_chip_t {
        timeout_ms should be a timeout (in milliseconds) before the function returns ESP_ERR_TIMEOUT. This is useful to avoid hanging
        if the chip is otherwise unresponsive (ie returns all 0xFF or similar.)
     */
-    esp_err_t (*wait_idle)(esp_flash_t *chip, unsigned timeout_ms);
+    esp_err_t (*wait_idle)(esp_flash_t *chip, uint32_t timeout_us);
 
     /* Configure both the SPI host and the chip for the read mode specified in chip->read_mode.
      *

components/spi_flash/spi_flash_os_func_app.c

@@ -96,7 +96,7 @@ static IRAM_ATTR esp_err_t spi1_end(void *arg)
 #endif
 }
 
-static IRAM_ATTR esp_err_t delay_us(void *arg, unsigned us)
+static IRAM_ATTR esp_err_t delay_us(void *arg, uint32_t us)
 {
     esp_rom_delay_us(us);
     return ESP_OK;

components/spi_flash/spi_flash_os_func_noos.c

@@ -64,7 +64,7 @@ static IRAM_ATTR esp_err_t end(void *arg)
     return ESP_OK;
 }
 
-static IRAM_ATTR esp_err_t delay_us(void *arg, unsigned us)
+static IRAM_ATTR esp_err_t delay_us(void *arg, uint32_t us)
 {
     esp_rom_delay_us(us);
     return ESP_OK;