[NFC] Fix camelCase variable name following fix for dev/core#1435

[seamuslee001]

Overview

Fixes camel casing issue pointed out by @aydun and @yashodha

ping @mattwire @eileenmcnaughton

[civibot]

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[jusfreeman]

@seamuslee001 can you just use the same name as retrieved, rather than introduce a different name in the variable?

So do this:
$memberId = CRM_Utils_Request::retrieve('memberId', 'Positive', $this);

Instead of this:
$membershipId = CRM_Utils_Request::retrieve('memberId', 'Positive', $this);

Just keeps things simple.

[eileenmcnaughton]

Hmm my version of keeping things simple is aligning everything with the field name which I thought about doing last patch - ie $contribution_membership_id.

I would say this change is 'better in than out'

[eileenmcnaughton]

@seamuslee001 style issue

[seamuslee001]

sorted @eileenmcnaughton