firmware: arm_ffa: Move comment before the field it is documenting

This is consistent with the other comments in the struct.
Co-developed-by: Andrew Walbran <qwandor@google.com>
Signed-off-by: Andrew Walbran <qwandor@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20221116170335.2341003-3-qperret@google.comSigned-off-by: Will Deacon <will@kernel.org>

include/linux/arm_ffa.h

@@ -244,11 +244,11 @@ struct ffa_mem_region_attributes {
 	 */
 #define FFA_MEM_RETRIEVE_SELF_BORROWER	BIT(0)
 	u8 flag;
-	u32 composite_off;
 	/*
 	 * Offset in bytes from the start of the outer `ffa_memory_region` to
 	 * an `struct ffa_mem_region_addr_range`.
 	 */
+	u32 composite_off;
 	u64 reserved;
 };