arm: remove unused variables from test

arm: remove unused variables from test

This is just a minor issue I found with a previous test
of mine that caused it to fail in C++ mode due to these
unused const variables being uninitialised. I forgot to
remove these after removing some test cases that did use
them. I removed the test cases, because I came to the
conclusion that the const-ness of the immediate was
irrelevant to the test itself.
Removing the variables now makes the test PASS for C++.

gcc/testsuite/ChangeLog:

	* gcc.target/arm/mve/intrinsics/mve_intrinsic_type_overloads-fp.c: Remove unused variables.
	* gcc.target/arm/mve/intrinsics/mve_intrinsic_type_overloads-int.c: Remove unused variables.