bpf: Fix propagation of 32 bit unsigned bounds from 64 bit bounds

      Similarly as b02709587ea3 ("bpf: Fix propagation of 32-bit signed bounds
from 64-bit bounds."), we also need to fix the propagation of 32 bit
unsigned bounds from 64 bit counterparts. That is, really only set the
u32_{min,max}_value when /both/ {umin,umax}_value safely fit in 32 bit
space. For example, the register with a umin_value == 1 does /not/ imply
that u32_min_value is also equal to 1, since umax_value could be much
larger than 32 bit subregister can hold, and thus u32_min_value is in
the interval [0,1] instead.

Before fix, invalid tracking result of R2_w=inv1:

  [...]
  5: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0) R10=fp0
  5: (35) if r2 >= 0x1 goto pc+1
  [...] // goto path
  7: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2=inv(id=0,umin_value=1) R10=fp0
  7: (b6) if w2 <= 0x1 goto pc+1
  [...] // goto path
  9: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2=inv(id=0,smin_value=-9223372036854775807,smax_value=9223