nvmem: u-boot-env: improve coding style

1. Prefer kzalloc() over kcalloc()
   See memory-allocation.rst which says: "to be on the safe side it's
   best to use routines that set memory to zero, like kzalloc()"
2. Drop dev_err() for u_boot_env_add_cells() fail
   It can fail only on -ENOMEM. We don't want to print error then.
3. Add extra "crc32_addr" variable
   It makes code reading header's crc32 easier to understand / review.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20231221173421.13737-5-zajec5@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Rafał Miłecki

drivers/nvmem/u-boot-env.c

@@ -132,6 +132,7 @@ static int u_boot_env_parse(struct u_boot_env *priv)
 	size_t crc32_data_offset;
 	size_t crc32_data_len;
 	size_t crc32_offset;
+	__le32 *crc32_addr;
 	size_t data_offset;
 	size_t data_len;
 	size_t dev_size;
@@ -143,7 +144,7 @@ static int u_boot_env_parse(struct u_boot_env *priv)
 
 	dev_size = nvmem_dev_size(nvmem);
 
-	buf = kcalloc(1, dev_size, GFP_KERNEL);
+	buf = kzalloc(dev_size, GFP_KERNEL);
 	if (!buf) {
 		err = -ENOMEM;
 		goto err_out;
@@ -175,7 +176,8 @@ static int u_boot_env_parse(struct u_boot_env *priv)
 		data_offset = offsetof(struct u_boot_env_image_broadcom, data);
 		break;
 	}
-	crc32 = le32_to_cpu(*(__le32 *)(buf + crc32_offset));
+	crc32_addr = (__le32 *)(buf + crc32_offset);
+	crc32 = le32_to_cpu(*crc32_addr);
 	crc32_data_len = dev_size - crc32_data_offset;
 	data_len = dev_size - data_offset;
 
@@ -188,8 +190,6 @@ static int u_boot_env_parse(struct u_boot_env *priv)
 
 	buf[dev_size - 1] = '\0';
 	err = u_boot_env_add_cells(priv, buf, data_offset, data_len);
-	if (err)
-		dev_err(dev, "Failed to add cells: %d\n", err);
 
 err_kfree:
 	kfree(buf);