phy: qcom: m31-eusb2: clear PLL_EN during init

The driver currently sets bit 0 of USB_PHY_CFG1 (PLL_EN) during PHY
initialization. According to the M31 EUSB2 PHY hardware documentation,
this bit is intended only for test/debug scenarios and does not control
mission mode operation. Keeping PLL_EN asserted causes the PHY to draw
additional current during USB bus suspend. Clearing this bit results in
lower suspend power consumption without affecting normal operation.

Update the driver to leave PLL_EN cleared as recommended by the hardware
documentation.

Fixes: 9c8504861cc4 ("phy: qcom: Add M31 based eUSB2 PHY driver")
Cc: stable@vger.kernel.org
Signed-off-by: Elson Serrao <elson.serrao@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://patch.msgid.link/20260217201130.2804550-1-elson.serrao@oss.qualcomm.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>