Correct bfin XPASSes

bfin-elf and bfin-linux differ.  This patch fixes these:
bfin-linux-uclibc  -XPASS: PR ld/14170
bfin-linux-uclibc  -XPASS: pr17068 link --as-needed lib in group
bfin-linux-uclibc  -XPASS: -Bsymbolic-functions
bfin-linux-uclibc  -XPASS: pr22374 function pointer initialization

	* testsuite/ld-elf/shared.exp (pr14170): Clear xfail for
	bfin-*-linux*.
	(pr17068, symbolic-func.so, pr22374): Likewise.