FixedDelta is defined as a struct of two 32bit values with architecture (endiannes)
independent order:
typedef struct _UInteger64 {
	uint32_t	lsb;
	uint32_t	msb;
} _UInteger64;

For WRPC the order of lsb and msb in 64bit type (not _UInteger64) is different,
so direct cast between _(U)Integer64 and regular 64bit types is not allowed.

Signed-off-by: Adam Wujek <adam.wujek@creotech.pl>