RISC-V: Move fortran testcase to gfortran.target

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/fortran/pr111395.f90: Move this file to...
	* gfortran.target/riscv/rvv/pr111395.f90: ...here.
	* gcc.target/riscv/rvv/fortran/pr111566.f90: Move this file to...
	* gfortran.target/riscv/rvv/pr111566.f90: ...here.
	* gcc.target/riscv/rvv/rvv-fortran.exp: Move this file to...
	* gfortran.target/riscv/rvv/rvv.exp: ...here.