Revert "libm: sqrt and sqrtf via ARM vsqrt instruction."

This reverts commit 71f7458c0890368e6b0c2706bb83493548a72baf.
libm: sqrt and sqrtf via ARM vsqrt instruction.

Optimized sqrt and sqrtf for arm by using hardware
opcode for sqrt rather than generic slow portable
code.

Change-Id: I9888d58547bcfca7dfc1400d3e7e222599167249