flash_map: Increase minimum supported write align via flash_area_align

Signed-off-by: Gustavo Henrique Nihei <gustavo.nihei@espressif.com>
diff --git a/boot/espressif/port/esp_mcuboot.c b/boot/espressif/port/esp_mcuboot.c
index 556e422..4dd03b9 100644
--- a/boot/espressif/port/esp_mcuboot.c
+++ b/boot/espressif/port/esp_mcuboot.c
@@ -239,7 +239,7 @@
     return 0;
 }
 
-size_t flash_area_align(const struct flash_area *area)
+uint32_t flash_area_align(const struct flash_area *area)
 {
     return 4;
 }