Fixup unaligned load/store cost for znver5

Fixup unaligned load/store cost for znver5

Currently unaligned YMM and ZMM load and store costs are cheaper than
aligned which causes the vectorizer to purposely mis-align accesses
by adding an alignment prologue.  It looks like the unaligned costs
were simply copied from the bogus znver4 costs.  The following makes
the unaligned costs equal to the aligned costs like in the fixed znver4
version.

	* config/i386/x86-tune-costs.h (znver5_cost): Update unaligned
	load and store cost from the aligned costs.