tools/cpupower: display residency value in idle-info

Update cpuidle tool to display the residency value of cpuidle
states. This addition provides a clearer and more detailed view
of idle state information when using cpuidle-info.

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 Before Patch:
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 $ cpupower idle-info
 CPUidle driver: intel_idle
 CPUidle governor: menu
 analyzing CPU 28:

 Number of idle states: 3
 Available idle states: POLL C1 C1E
 POLL:
 Flags/Description: CPUIDLE CORE POLL IDLE
 Latency: 0
 Usage: 7448
 Duration: 207170
 C1:
 Flags/Description: MWAIT 0x00
 Latency: 2
 Usage: 7023
 Duration: 3736853
 C1E:
 Flags/Description: MWAIT 0x01
 Latency: 10
 Usage: 18468
 Duration: 11396212

 --------------------------------
 After Patch:
 --------------------------------
 $ cpupower idle-info
 CPUidle driver: intel_idle
 CPUidle governor: menu
 analyzing CPU 12:

 Number of idle states: 3
 Available idle states: POLL C1 C1E
 POLL:
 Flags/Description: CPUIDLE CORE POLL IDLE
 Latency: 0
 Residency: 0
 Usage: 1950
 Duration: 38458
 C1:
 Flags/Description: MWAIT 0x00
 Latency: 2
 Residency: 2
 Usage: 10688
 Duration: 7133020
 C1E:
 Flags/Description: MWAIT 0x01
 Latency: 10
 Residency: 20
 Usage: 22356
 Duration: 15687259
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Signed-off-by: Aboorva Devarajan <aboorvad@linux.ibm.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>