fix matrix_power documentation bug (#108585)
The torch.linalg.matrix_power documentation suggests using the formula
`matrix_power(torch.linalg.solve(A, B), n) == matrix_power(A, -n) @ B`
to avoid negative matrix powers. But the ordering of the left side is not correct. This patch fixes it to:
`torch.linalg.solve(matrix_power(A, n), B) == matrix_power(A, -n) @ B`
Pull Request resolved: https://github.com/pytorch/pytorch/pull/108585
Approved by: https://github.com/lezcano
