You don't need a cursor for this, it's a simple UPDATE...FROM:
UPDATE l SET
CAL_HEADER_ID= @PVC_CALENDAR_HEADER_ID,
PERIOD_NAME= t.ATTRIBUTE2, --@lvc_period_name,
FROM_DATE= CONVERT(VARCHAR(11),LTRIM(RTRIM(t.ATTRIBUTE3)), 106), --@ld_from_date_1,
TO_DATE= CONVERT(VARCHAR(11),LTRIM(RTRIM(t.ATTRIBUTE4)), 106), --@ld_to_date_1,
QUARTER_NUM= t.ATTRIBUTE5, --@li_quarter_num,
F_YEAR= t.ATTRIBUTE6, --@lvc_f_year,
ADJUSTING_PERIOD = t.ATTRIBUTE7, --@li_adjusting_period,
TRN= @PBI_TRN,
STATUS= 1,
SESSION_ID= @PBI_SESSION_ID
FROM GL_CALENDAR_LINES l
INNER JOIN TEMP_table t
ON t.ACTUAL_LINE_ID = l.CAL_LINE_ID
WHERE t.ACTION_FLAG = 'U'
AND t.SESSION_ID = @PBI_SESSION_ID
AND t.TRN=@PBI_TRN
For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden