The specification allow list-directed PRINT and WRITE statements to
appear in device code. This patch relax the semantic check to allow
them.
3.6.11.
List-directed PRINT and WRITE statements to the default unit may be used
when compiling for compute capability 2.0 and higher; all other uses of
PRINT and WRITE are disallowed.
In section 3.4.2, some example of illegal data transfer using expression
are given. One of it is when multiple device objects are part of an
expression in the rhs. Current implementation allow a single device
object in such case. This patch adds a similar restriction.
