dsp: firmware_update: Avoid integer overflow

A large fw_device_pkg_data_length could cause uint16_t
calc_min_record_length to wrap around. Instead use a size_t.

Change-Id: I1e0ee5a350d82cb477fd0955a11ded659a5c5933
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
diff --git a/src/dsp/firmware_update.c b/src/dsp/firmware_update.c
index 5c57171..09c4f66 100644
--- a/src/dsp/firmware_update.c
+++ b/src/dsp/firmware_update.c
@@ -436,7 +436,7 @@
 	uint16_t applicable_components_length =
 		component_bitmap_bit_length /
 		PLDM_FWUP_COMPONENT_BITMAP_MULTIPLE;
-	uint16_t calc_min_record_length =
+	size_t calc_min_record_length =
 		sizeof(struct pldm_firmware_device_id_record) +
 		applicable_components_length +
 		data_record->comp_image_set_version_string_length +