Fix inverted statements in m88k_analyze_prologue

Fix inverted statements in m88k_analyze_prologue

These two statements were inverted by mistake in commit "Replace some
xmalloc-family functions with XNEW-family ones".  It obviously doesn't
make sense to have them in this order, which is why I am pushing this as
obvious.

gdb/ChangeLog:

	* m88k-tdep.c (m88k_analyze_prologue): Fix inverted allocation
	statements.