bnxt_en: add unlocked version of bnxt_refclk_read

bnxt_en: add unlocked version of bnxt_refclk_read

Serialization of PHC read with FW reset mechanism uses ptp_lock which
also protects timecounter updates. This means we cannot grab it when
called from bnxt_cc_read(). Let's move locking into different function.

Fixes: 6c0828d00f07 ("bnxt_en: replace PTP spinlock with seqlock")
Signed-off-by: Vadim Fedorenko <vadfed@meta.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Link: https://patch.msgid.link/20241107214917.2980976-1-vadfed@meta.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>