aarch64: update ampere1 vectorization cost

aarch64: update ampere1 vectorization cost

The original submission of AmpereOne (-mcpu=ampere1) costs occurred
prior to exhaustive testing of vectorizable workloads against
hardware.

Adjust the vector costs to achieve the best results and more closely
match the underlying hardware.

gcc/ChangeLog:

	* config/aarch64/aarch64.cc: Update vector costs for ampere1.

Co-Authored-By: Jiangning Liu <jiangning.liu@amperecomputing.com>
Co-Authored-By: Manolis Tsamis <manolis.tsamis@vrull.eu>