[h8300] Fix ambiguous .md attribute uses

[h8300] Fix ambiguous .md attribute uses

This patch is part of a series that fixes ambiguous attribute
uses in .md files, i.e. cases in which attributes didn't use
<ITER:ATTR> to specify an iterator, and in which <ATTR> could
have different values depending on the iterator chosen.

No behavioural change -- produces the same code as before.

2019-07-06  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* config/h8300/h8300.md (*push1_h8300hs_<mode>): Explicitly
	specify the mode iterator referenced by <mode>, giving...
	(*push1_h8300hs_<QHI:mode>): ...this.

From-SVN: r273160