fw_printenv: Fix variable values getting truncated on '=' symbols
fw_printenv: Fix variable values getting truncated on '=' symbols

Using the current fw_printenv implementation to print the value for a
single grub variable results in truncated output if the value field
contains '=' symbols.

e.g.

  # fw_printenv othbootargs
  othbootargs=isolcpus

instead of the expected:

  # fw_printenv othbootargs
  othbootargs=isolcpus=7 nohz_full=7

Fix the 'cut' call used to extract the variable value in
show_variable_grub() to include the rest of the line after the 'key' field.

Signed-off-by: Gratian Crisan <17cf39b7426cfdea7dd491f7105a23841aaa302f@ni.com>

ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt,ni/meta-nilrt