net: ipa: fix one GSI register field width

The width of the R_LENGTH field of the EV_CH_E_CNTXT_1 GSI register
is 24 bits (not 20 bits) starting with IPA v5.0.  Fix this.

Fixes: faf0678e

 ("net: ipa: add IPA v5.0 GSI register definitions")
Signed-off-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20231122231708.896632-1-elder@linaro.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>