Add regex pattern case_insensitive param and underscore

Changes:
     - Add "_" underscore in regex expression
     - Add case_insensitive param to regex filtering inventory matches
       Example:
             "/xyz/openbmc_project/inventory/system/chassis/motherboard/CPU_0"
             "/xyz/openbmc_project/inventory/system/chassis/motherboard/cpu0"

Tested Pattern such as:
    - lower case "cpu"
    - upper case "CPU"
    - which has underscore in the endpoint e.g. "fan"
      "/xyz/openbmc_project/sensors/fan_tach/fan0_0"

Example Robot test:

Example Inventory
    [Documentation]  Example inventory.
    [Tags]  Example_Inventory

    ${cpu_list}=  Get Endpoint Paths  /xyz/openbmc_project/inventory/  cpu
    Log To Console  \n Lower case(cpu): ${cpu_list}
    ${cpu_list}=  Get Endpoint Paths  /xyz/openbmc_project/inventory/  CPU
    Log To Console  \n Upper case(CPU): ${cpu_list}
    ${fan_list}=  Get Endpoint Paths  /xyz/openbmc_project/sensors/  fan
    Log To Console  \n ${fan_list}

Change-Id: I2345b780ee135c753fa9aaab901866abb232d3e8
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/lib/utils.robot b/lib/utils.robot
index e4d812c..1c878c9 100755
--- a/lib/utils.robot
+++ b/lib/utils.robot
@@ -503,7 +503,7 @@
     # For a given string, look for prefix and suffix for matching expression.
     # Start of string followed by zero or more of any character followed by
     # any digit or lower case character.
-    ${resp}=  Get Matches  ${list}  regexp=^.*[0-9a-z_].${endpoint}\[0-9a-z]*$
+    ${resp}=  Get Matches  ${list}  regexp=^.*[0-9a-z_].${endpoint}\[_0-9a-z]*$  case_insensitive=${True}
 
     [Return]  ${resp}