improve-nr_ul_channel_estimation

improve code readability, add avx2 speedup

OAI RAN-Container-Parent build (2275): Your merge request has none of the mandatory labels:

• BUILD-ONLY
• 4G-LTE
• 5G-NR
• CI

Not performing CI due to lack of labels

added 5G-NR label

OAI RAN-Container-Parent build (2275): failed (https://jenkins-oai.eurecom.fr/job/RAN-Container-Parent/2275/)

OAI RAN-CI-develop build (3644): Some Changed files in Merge Request DO NOT follow OAI Formatting Rules

OAI RAN-CI-develop build (3644): Some modified files in Merge Request MAY have INTRODUCED WARNINGS (openair1/PHY/TOOLS/tools_defs.h)

OAI RAN-CI-develop build (3644): failed (https://open5glab.eurecom.fr:8083/jenkins/job/RAN-CI-develop/3644/)

added 19 commits

• ae43051f...50916825 - 18 commits from branch develop
• 9fc6d012 - improve-nr_ul_channel_estimation

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OAI RAN-CI-develop build (3678): Some Changed files in Merge Request DO NOT follow OAI Formatting Rules

OAI RAN-CI-develop build (3678): Some modified files in Merge Request MAY have INTRODUCED WARNINGS (openair1/PHY/TOOLS/tools_defs.h)

OAI RAN-CI-develop build (3678): failed (https://open5glab.eurecom.fr:8083/jenkins/job/RAN-CI-develop/3678/)

OAI RAN-Container-Parent build (2310): failed (https://jenkins-oai.eurecom.fr/job/RAN-Container-Parent/2310/)

added 66 commits

• 9fc6d012...72bf1b1d - 65 commits from branch develop
• 96df8311 - improve-nr_ul_channel_estimation

Compare with previous version

@rmagueta please review my merge of function nr_pusch_channel_estimation()

OAI RAN-CI-develop build (3703): Some Changed files in Merge Request DO NOT follow OAI Formatting Rules

OAI RAN-CI-develop build (3703): Some modified files in Merge Request MAY have INTRODUCED WARNINGS (openair1/PHY/TOOLS/tools_defs.h)

OAI RAN-CI-develop build (3703): failed (https://open5glab.eurecom.fr:8083/jenkins/job/RAN-CI-develop/3703/)

OAI RAN-Container-Parent build (2335): failed (https://jenkins-oai.eurecom.fr/job/RAN-Container-Parent/2335/)