RISC-V: Fix rvv intrinsic pragma tests dejagnu selector

Adding rvv related flags (i.e. --param=riscv-autovec-preference) to
non vector targets bypassed the dejagnu skip test directive. Change the
target selector to skip if rvv is enabled

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/base/abi-1.c: change selector
	* gcc.target/riscv/rvv/base/pragma-2.c: ditto
	* gcc.target/riscv/rvv/base/pragma-3.c: ditto

Signed-off-by: Edwin Lu <ewlu@rivosinc.com>