[AMD] Added instr.sched guards for the FA-like kernels

[ravil-mobile]

Extended AMDGPU instruction scheduling for the Flash Attention like kernels. The introduced source code changes adds sched.barriers at the beginning and at the end of each scf.For op (called guards) which contains at least 2 tt.Dot, tt.reduce and at least one math::Exp2Op ops. The guards prevent moves of instructions from basic block adjacent to the bodies for for-loops. According to test results, it results in increase performance for the FA kernels due to a reduction of VGPRs spilling.

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