tests: drivers: flash: common: Fixing the overlap case

For the flash with the block size equal to or smaller than 64 bytes,
using a specific "32" bytes for adding for destination_offset and "32"
bytes for subtracting the size that need to copy is not correct.

As a solution, I will add one-fourth of a block size for the
destination_offset and modify the size that need to copy to
[block size + one-fourth of a block size].

Signed-off-by: Khoa Nguyen <khoa.nguyen.xh@renesas.com>

Author: khoa-nguyen-18

tests/drivers/flash/common/src/main.c

@@ -462,8 +462,8 @@ ZTEST(flash_driver, test_flash_copy)
 
 	/* copy with overlapping ranges should fail */
 	test_flash_copy_inner(flash_dev, page_info.start_offset, flash_dev,
-			      page_info.start_offset + 32, page_info.size - 32, buf, sizeof(buf),
-			      -EINVAL);
+			      page_info.start_offset + (page_info.size / 4),
+			      page_info.size - (page_info.size / 4), buf, sizeof(buf), -EINVAL);
 }
 
 ZTEST_SUITE(flash_driver, NULL, NULL, flash_driver_before, NULL, NULL);