[builtins] Unify the softfloat division implementation

This patch replaces three different pre-existing implementations of
__div[sdt]f3 LibCalls with a generic one - like it is already done for
many other LibCalls.

Reviewed By: sepavloff

Differential Revision: https://reviews.llvm.org/D85031

GitOrigin-RevId: 0e90d8d4fed8c8cac70700acfdef6fc2ca2d482d
7 files changed